Developing a Coherent Undersea Setting

[Scalenex]

I checked the D&D wikis and the fluff details on undersea creatures are pretty sparse compared to land creatures.

The Monstrous Manuals I flipped through, aquatic creatures basically have a stat block and a couple paragraphs of explanation, mostly explaining their battle tactics.

Before I reinvent the wheel, is there a very fluff heavy D&D source book developing the undersea biome in detail?

I'm going to use Mer-People to refer to any intelligent aquatic sea humans. I'm probably going to have traditional merfolk, some kind of shark people, some kind of crab people, some kind of squid people. i may or may not have terrifying sponge people living in pineapple themed undersea dungeons.


-What do Mer-people use for pen and paper? If they don't have a better substitute that clay tablets, is literacy basically unheard of.

-How do aquatic adventurers use magic scrolls and potions?

-How do Mer-People talk? Can they talk like land people with minimal fuss or do they do need hand signals or something exotic like telepathy or electrical currents to speak?

-How do Mer-People get metal tools and weapons? Can they?

-Would Mer-People have to stick mostly to the ocean levels that get lots of sunlight? Would they mostly have to stick close to the sea floor? Would most Mer-People be nomadic?


I got more questions, but I'll leave it there. I guess the central thing, I'd like to see what day-to-day life is like under the sea. I'd like to figure out what the political situation is. Since my land setting doesn't have a clear fictional analog to Ancient Rome, I'm thinking of making a Water Rome. I'm not sure if I want Water Rome to be in an expansionary phase, Pax Romana phase, or on the decline.

I like the idea of the Water Roman Senators having too political camps. Should we avoid contact with the surface dwellers or should we seek out greater contact. These political factions would be nicknamed Deeps and Shallows respectively.

I haven't gotten much further than that.

[sandmote]

5e's Ghosts of Saltmarsh has a section near the end laying out a a bunch of fluff. There's also a section of expanded monsters for aquatic settings.

I think the big thing here is that there isn't going to be a single biome. Kelp forests, sandy plains, and massive coral reefs are each fundamentally different in resources and environment, as are cold and hot seeps in deeper waters.

I'm going to use Mer-People to refer to any intelligent aquatic sea humans. I'm probably going to have traditional merfolk, some kind of shark people, some kind of crab people, some kind of squid people. i may or may not have terrifying sponge people living in pineapple themed undersea dungeons.

Merrow are the traditional shark race in D&D, to my knowledge.

-What do Mer-people use for pen and paper? If they don't have a better substitute that clay tablets, is literacy basically unheard of.

-How do aquatic adventurers use magic scrolls and potions?

-How do Mer-People talk? Can they talk like land people with minimal fuss or do they do need hand signals or something exotic like telepathy or electrical currents to speak?

-How do Mer-People get metal tools and weapons? Can they?

-Would Mer-People have to stick mostly to the ocean levels that get lots of sunlight? Would they mostly have to stick close to the sea floor? Would most Mer-People be nomadic?

I'd go with bone or parchment made from a marine animal. Maintaining and then firing clay tablet is likely to be a problem. Vellum-equivalent scrolls only, I suspect. Potions could be stored in squeezable pouches, this being limited to the specific types of potions safe to store in organic materials instead of glass.

Sound travels further underwater, so having a spoken language probably isn't a problem. On the other hand, electrical communication could be used to talk without being "overheard," by other species, probably by the shark people.

The first issue with metal underwater is that most metals are very quickly corroded in seawater. If they trade for or produce any metal, it would probably be bronze, which lasts an unusually long time. On the bright side, bronze means either trading or mining significant amounts of copper and tin, so securing these materials can be a reason for imperial expansion into other regions, or a reason for decline (if those metal are cut off). Between metalworking and trade, the undersea races would want secure holdings on the surface.

The mer-people's culture would probably depend on the local environment. Farming would be easiest on the surface (seaweed) and in cold seeps (shellfish) maybe with delicacies farmed on small islands or hot seeps. In relatively barren mud flats or undersea plains I'd expect them to be semi-nomadic, taking up residence near migrating animals or a smaller reef for part of the year.

The largest cities would probably be situated with a trading quarter on a sandbar along a major trade route with a large area for producing food around them. The main military regions (away from political borders) would be the ones producing crucial tin and copper for whoever controls them.

[Jendekit]

There were two episodes on the Dungeon Master's Block podcast that specifically talked about underwater gaming with part-time game developer Rich Howard (who I might point out has a degree in marine biology). Episode 19: Under the Sea and episode 37: Return to the Depths, and there's a couple threads on their forum where the board created an undersea race or two.

[sktarq]

This has been all over the map depending on editions...

"Shark people" has varies from shaguin (with Malenti-links to sea-elves), were-sharks etc.

merrow were water-ogres for a time but that could have changed

There was splat book of something similar for 3e focusing on the history of the starsea in FR which may be worth a lookup.

Merfolk were said to use a more highly viscous potion system in squeeze pouches.

Many tools would have to be traded for and so they may have only a stone age technology system. Which doesn't imply a non-complex society.

Tanning would be an issue so leather (including vellum) would be a hard sell.

In terms of voice I would have to say that they have vocal systems that can adjust to both air and water depending on what they are breathing


There is a thread in the forum discussing underwater civ tech that should still be findable where a lot of things go into more detail.

[sandmote]

"Shark people" has varies from shaguin (with Malenti-links to sea-elves), were-sharks etc.

merrow were water-ogres for a time but that could have changed

I forgot about the sahuagin. In 5e merrow are demonically infused merfolk with sharklike features.

Tanning would be an issue so leather (including vellum) would be a hard sell.

Parchment and vellum aren't tanned. They are dried IRL, but you can probably get around that by declaring the parchment used to come from an underwater creature and made with a slightly different process.

The best older discussion on this subject I found is here. It mainly focuses on the effects of pressure, though.

[Quizatzhaderac]

-What do Mer-people use for pen and paper? If they don't have a better substitute that clay tablets, is literacy basically unheard of.

A civilization can function without most people being able to read. For example the Odyssey mentions reading/writing once and it's pretty clear the author is unfamiliar with the practice. There are techniques to help memorizing large texts easier that tended to be very common in societies without mass literacy.

Also stone tablets mean almost nobody is writing, but stone carvings can be read many, many times.

One thing you can't have is a bureaucracy. But really, is that a bug or a feature?

If you really want a temporary writing you could have the messages carved into something soft. You could also have certain knots represent certain words, and people make messages by creating a sequence of knots in a string. (or tying smaller strings to the main string in specific knots).

-How do aquatic adventurers use magic scrolls and potions?

I'd say entirely forget about the physical form of the scroll. Anything with a sufficiently complicated/detailed shape would work, just keep the element that it needs to be created by a magic user that knows what they are doing. Unlike regular writing, magical writing is supposed to be weird/ difficult/complex/arcane, so things that are impractical paper substitutes are okay. Statuettes made of fish bones, knittings of kelp?

--How do Mer-People get metal tools and weapons? Can they?

Probably not for vanilla mer-people. Metalworking requires an insulator (air) to separate the hot metal from the person working it. Having nothing but water between the smith and the metal means either the metal is too cold or the smith is too hot.

You could have a race that's able to live in volcanic vents (and immune to fire damage) that's able to work metal.

You might also have trade from land or under-dark.

You could also make up metals that don't require heat. Notably cold-iron is clearly not the real world equivalent, so it might as well be made by fish people without a blast furnace.

Also stone working could still be a thing. Although different mining technologies would be needed.

For a setting remotely like D&D could expect monsters with supernaturally strong/hard bones/teeth and pouches of strong chemicals.

-Would Mer-People have to stick mostly to the ocean levels that get lots of sunlight? Would they mostly have to stick close to the sea floor? Would most Mer-People be nomadic?

The food chain starts with either photosynthesis or chemosynthesis. Photosynthesis is much more common in our world.

Photosynthesis happens only near the surface. Creatures generally feed either near the top (where algae live) or at the bottom (where dead things fall to). If we're talking about large, intelligent creatures, there's no problem with them feeding/ farming near the surface/ shallows and resting/crafting near the bottom.

Chemosynthesis is rare in or world, mainly because our world is old. A younger world could easily have vast amounts of chemical energy available at the ocean floor that's stable over the coarse of centuries.

regions: As I see it, there are six types of terrain.

Shallows: Sunlight touches floor. Has plants. Lively regions. Typically also has amphibious animals as well. Technical name Neritic zone. If you only do one zone, do this one.

Photic zone: The surface of most of the ocean (200 meters down). Most algae live there. Growth tends to be limited by solid nutrients. Could be "farmed" by introducing fertilizers which would cause algae blooms.

Midnight zone: No light, no solid surface. Mainly a transitional zone. Probably a good place to hide.

Vanilla Sea floor: Few miles down. Stuff can be built and mined. Food is mostly dead things of stuff that eat dead things.

Hydro thermal vents: Hot water, within tunneling distance of magma. Source of chemosynthetic life.

Cold seeps: Methane seeping into water. Source of chemosynthetic life. Potentially much more common in a young world.

[Grek]

Cerulean Seas is a Pathfinder book, but the setting questions all translate into whatever version of D&D you're using just fine. Particular answers include:

• Scrolls are written using jellied squid ink on a cartilage based vellum or on parchment made from a particularly fibrous sort of seaweed. Sea urchin quills are used as a stylus.
• Potions (and most beverages) are prepared using a dense immiscible oil as the base rather than water. This oil is also popular for storing meat, as it keeps sharks and other animals from smelling the blood.
• There are several species of aquatic humanoids, all of which can be understood underwater (think Goblet of Fire, where Harry has to stick his head in the bath to hear the Merfolk's recorded message) and several of which can be understood on land due to shapeshifting or the ability to breathe air in addition to water.
• Aquatic species who are able to walk on land, even for short periods of time, tend to establish coastal settlements where they do their metal-working. Those who cannot do so either trade for their metal from those who can, or do without. In addition to Bronze, the book also introduces two non-corroding steel alloys (auranite and mithrite) which are made using moderate amounts of gold and trace amounts of mithril respectively.

Where people live is mostly a question of where they can find food (and water, but finding water in the ocean isn't hard). And it turns out that the oceans mostly look like Australia when it comes to food distribution: lots of people and lots of farms out on the coasts with a huge empty wasteland in the middle with a lot more wild animals and a lot less people in it.

Most of the photosynthesis happens within 1000m of the surface, a region called the pelagic zone. Near the coast, this is filled with kelp and coral and the like and serves as the primary agricultural region for any big underwater kingdom. Once you get out past the continental shelf, you hit the 'Outback' portion of the ocean. There's still free floating algae and even sargassum, but it doesn't grow nearly as much as kelp or coral does and anything that wants to eat it has to either be constantly swimming or wait for it to die and fall to the bottom of the ocean as 'marine snow'. A related concept is a 'whale fall' which is pretty much exactly what it sounds like. Instead of something tiny (like a single plankton) dying and falling to the bottom something big (like a whole whale) dies and falls to the bottom instead. In the real world, this causes a temporary boom in population, but in a fantasy setting I imagine it would have nomadic tribes of crab people staking a claim and harvesting entire whales before moving on.

[Scalenex]

Sorry for the belated response, the Order of Stick forums were down a long time, at least for me.

5e's Ghosts of Saltmarsh has a section near the end laying out a a bunch of fluff. There's also a section of expanded monsters for aquatic settings.

I think the big thing here is that there isn't going to be a single biome. Kelp forests, sandy plains, and massive coral reefs are each fundamentally different in resources and environment, as are cold and hot seeps in deeper waters.

Good idea

Merrow are the traditional shark race in D&D, to my knowledge.

I was underwhelmed by the fluff I found on Merrow.

I'd go with bone or parchment made from a marine animal. Maintaining and then firing clay tablet is likely to be a problem. Vellum-equivalent scrolls only, I suspect. Potions could be stored in squeezable pouches, this being limited to the specific types of potions safe to store in organic materials instead of glass.

Merfolk were said to use a more highly viscous potion system in squeeze pouches.

I certainly like the idea of parchment from marine animal skins. Squeezable postions would work but what about potions in a chewable form? It would admittedly be a bit slower to ingest.

Sound travels further underwater, so having a spoken language probably isn't a problem. On the other hand, electrical communication could be used to talk without being "overheard," by other species, probably by the shark people.

Agreed on both counts

The first issue with metal underwater is that most metals are very quickly corroded in seawater. If they trade for or produce any metal, it would probably be bronze, which lasts an unusually long time. On the bright side, bronze means either trading or mining significant amounts of copper and tin, so securing these materials can be a reason for imperial expansion into other regions, or a reason for decline (if those metal are cut off). Between metalworking and trade, the undersea races would want secure holdings on the surface.

I figure alchemy could rust proof metal. The process might make the metal item or tool double or triple the cost but it’d be the only feasible way to have metal weapons under the sea.

The mer-people's culture would probably depend on the local environment. Farming would be easiest on the surface (seaweed) and in cold seeps (shellfish) maybe with delicacies farmed on small islands or hot seeps. In relatively barren mud flats or undersea plains I'd expect them to be semi-nomadic, taking up residence near migrating animals or a smaller reef for part of the year.

The largest cities would probably be situated with a trading quarter on a sandbar along a major trade route with a large area for producing food around them. The main military regions (away from political borders) would be the ones producing crucial tin and copper for whoever controls them.

Good advice.

There were two episodes on the Dungeon Master's Block podcast that specifically talked about underwater gaming with part-time game developer Rich Howard (who I might point out has a degree in marine biology). Episode 19: Under the Sea and episode 37: Return to the Depths, and there's a couple threads on their forum where the board created an undersea race or two.

I will give this a look.

There was splat book of something similar for 3e focusing on the history of the starsea in FR which may be worth a lookup.

Anyone know the name of said book?

Many tools would have to be traded for and so they may have only a stone age technology system. Which doesn't imply a non-complex society.

I know this is logical but I would prefer the aquatic beings of my world be roughly on par with my landfolk.

Tanning would be an issue so leather (including vellum) would be a hard sell.

True, but I like the idea of leather clad merfolk warriors so I need to make up a fantasy explanation for them having some form of tanning like Sandmote suggested.

In terms of voice I would have to say that they have vocal systems that can adjust to both air and water depending on what they are breathing


There is a thread in the forum discussing underwater civ tech that should still be findable where a lot of things go into more detail.

A link would make me ever so happy!

The best older discussion on this subject I found is here. It mainly focuses on the effects of pressure, though.

Thankyou Sandmote!

A civilization can function without most people being able to read. For example the Odyssey mentions reading/writing once and it's pretty clear the author is unfamiliar with the practice. There are techniques to help memorizing large texts easier that tended to be very common in societies without mass literacy.

Also stone tablets mean almost nobody is writing, but stone carvings can be read many, many times.

One thing you can't have is a bureaucracy. But really, is that a bug or a feature?

If you really want a temporary writing you could have the messages carved into something soft. You could also have certain knots represent certain words, and people make messages by creating a sequence of knots in a string. (or tying smaller strings to the main string in specific knots).

I'd say entirely forget about the physical form of the scroll. Anything with a sufficiently complicated/detailed shape would work, just keep the element that it needs to be created by a magic user that knows what they are doing. Unlike regular writing, magical writing is supposed to be weird/ difficult/complex/arcane, so things that are impractical paper substitutes are okay. Statuettes made of fish bones, knittings of kelp?

Probably not for vanilla mer-people. Metalworking requires an insulator (air) to separate the hot metal from the person working it. Having nothing but water between the smith and the metal means either the metal is too cold or the smith is too hot.

You could have a race that's able to live in volcanic vents (and immune to fire damage) that's able to work metal.

I was thinking of taking a leaf out of Rick Riordans books and have Cyclopes be a heat proof undersea that can forge metal for aquatic people.

You might also have trade from land or under-dark.

That too.

You could also make up metals that don't require heat. Notably cold-iron is clearly not the real world equivalent, so it might as well be made by fish people without a blast furnace.

Every use green stuff epoxy? You mix the blue and yellow epoxy and the epoxy becomes malleable for several minutes but will eventual harden. My thought is to create an undersea variant of this. Two types of clay when mixed can create a super hard ceramic. Not as hard as iron or steel, but the ceramic weapons and armor is better than nothing.

Also stone working could still be a thing. Although different mining technologies would be needed.

Nod

For a setting remotely like D&D could expect monsters with supernaturally strong/hard bones/teeth and pouches of strong chemicals.

Very good idea.

The food chain starts with either photosynthesis or chemosynthesis. Photosynthesis is much more common in our world.

Photosynthesis happens only near the surface. Creatures generally feed either near the top (where algae live) or at the bottom (where dead things fall to). If we're talking about large, intelligent creatures, there's no problem with them feeding/ farming near the surface/ shallows and resting/crafting near the bottom.

Chemosynthesis is rare in or world, mainly because our world is old. A younger world could easily have vast amounts of chemical energy available at the ocean floor that's stable over the course of centuries.[/QUOTE]

My world is fairly young. Less than a million years old but who cares about science when you have SCIENCE! Some of my deities have created lifestones in the Underdark. The SCIENCE! of lifestones can create edible fungi out of nothing. This allows subterranean races and creatures to sustain more numbers than regular science would dictate.

I suppose lifestones are not different from undersea chemical vents except the chemical vents are REAL and actually do sustain impressive biomes.

regions: As I see it, there are six types of terrain.

Shallows: Sunlight touches floor. Has plants. Lively regions. Typically also has amphibious animals as well. Technical name Neritic zone. If you only do one zone, do this one.

Photic zone: The surface of most of the ocean (200 meters down). Most algae live there. Growth tends to be limited by solid nutrients. Could be "farmed" by introducing fertilizers which would cause algae blooms.

Midnight zone: No light, no solid surface. Mainly a transitional zone. Probably a good place to hide.

Vanilla Sea floor: Few miles down. Stuff can be built and mined. Food is mostly dead things of stuff that eat dead things.

Hydro thermal vents: Hot water, within tunneling distance of magma. Source of chemosynthetic life.

Cold seeps: Methane seeping into water. Source of chemosynthetic life. Potentially much more common in a young world.

Nice summary. I will save this to consult later.

Cerulean Seas is a Pathfinder book, but the setting questions all translate into whatever version of D&D you're using just fine.

Where people live is mostly a question of where they can find food (and water, but finding water in the ocean isn't hard). And it turns out that the oceans mostly look like Australia when it comes to food distribution: lots of people and lots of farms out on the coasts with a huge empty wasteland in the middle with a lot more wild animals and a lot less people in it.

Most of the photosynthesis happens within 1000m of the surface, a region called the pelagic zone. Near the coast, this is filled with kelp and coral and the like and serves as the primary agricultural region for any big underwater kingdom. Once you get out past the continental shelf, you hit the 'Outback' portion of the ocean. There's still free floating algae and even sargassum, but it doesn't grow nearly as much as kelp or coral does and anything that wants to eat it has to either be constantly swimming or wait for it to die and fall to the bottom of the ocean as 'marine snow'. A related concept is a 'whale fall' which is pretty much exactly what it sounds like. Instead of something tiny (like a single plankton) dying and falling to the bottom something big (like a whole whale) dies and falls to the bottom instead. In the real world, this causes a temporary boom in population, but in a fantasy setting I imagine it would have nomadic tribes of crab people staking a claim and harvesting entire whales before moving on.

Good advice.


Another thing I’m doing is changing my pantheon up. I’m a fan of Rick Riordian and I like that he gives his fictional representations of the Olympian gods a different personality and appearance for their Greek and Roman versions.

My world has nine deities, one for each alignment, but they are shaped by the thoughts, hopes and fears of their worshipers, so I plan to give them slightly different powers and personalities in their land and sea forms because aquatic people have different outlooks and priorities. Maybe I’ll make their underdark personalities different too. I think this will add character to my sea societies.

Some of my deities are gender flipping. I’m still working out the finer details. My land folk have a male moon god and female sun goddess and only one sea deity. The sea deity that the land folk think of as the goddess of the sea, to aquatic people is one of three see deity and in her case she is the sea deity that wants to strengthen ties between sea breathers an air breathers. That’s why the land folk think of her as the only sea deity. As far as sea folk are concerned, both the moon and sun are represented by male gods. They also view the three sea deities as the Three Daughters/Sisters of the Sea, and one of the sea goddesses is considered a male on land.

As far as the seafolk are concerned, there is Mother Sea and Father Sky. Life is made possible when Mother Sea and Father Sky join together. Father Sky provides “fire” to the sea by heating the waters and Mother Sea provides “water” to the sky by allowing evaporation.

My predatory Chaotic Evil deity, Maylar, is a male god on land and a female goddess in the sea. I figured the sea folk would view Maylar as a shark god and with most species of shark the female is larger and thicker skinned than the males on average.

I’m probably going to make my two sea floor deities males because I’m probably going to make them the patrons of crabs, and males tend to be larger than the females. That said, they are going to be minor gods, viewed as mere sidekicks to the Three Sisters of the Sea and Two Sons of the Father Sky.

I’m not sure if I’m going to give the aquatic people a god or goddess associated with land. As far as they are concerned, the landfolk are leeches or barnacles mooching off Father Sky and Mother Sea for their basic necessities.

So probably going with three sea goddesses, two sea floor gods, two sky gods, and two X-factors goddesses that travel between the realms.

[MrZJunior]

I’m not sure if I’m going to give the aquatic people a god or goddess associated with land. As far as they are concerned, the landfolk are leeches or barnacles mooching off Father Sky and Mother Sea for their basic necessities.

So maybe a trickster or thief god?

[sandmote]

I was underwhelmed by the fluff I found on Merrow.

Yeah, there isn't much underwater in d&d.

I certainly like the idea of parchment from marine animal skins. Squeezable postions would work but what about potions in a chewable form? It would admittedly be a bit slower to ingest.

As long as you account for chewable forms making potions harder to administer to others. Otherwise, just make sure your table isn't just going to descend into jokes about tide pods.

I figure alchemy could rust proof metal. The process might make the metal item or tool double or triple the cost but it’d be the only feasible way to have metal weapons under the sea.

That works. Simply replace my comments on copper and tin mining to refer to whatever alchemical material is being used.

True, but I like the idea of leather clad merfolk warriors so I need to make up a fantasy explanation for them having some form of tanning like Sandmote suggested.

You can use Gambesons instead of leather. Thick, quilted cloth does quite a bit at protecting the body.

Every use green stuff epoxy? You mix the blue and yellow epoxy and the epoxy becomes malleable for several minutes but will eventual harden. My thought is to create an undersea variant of this. Two types of clay when mixed can create a super hard ceramic. Not as hard as iron or steel, but the ceramic weapons and armor is better than nothing.

Ceramics are usually brittle, which may or may not also take place in your setting. An excellent idea for arrows and bolts though, given trees are unlikely to grow underwater.

Another thing I’m doing is changing my pantheon up. I’m a fan of Rick Riordian and I like that he gives his fictional representations of the Olympian gods a different personality and appearance for their Greek and Roman versions.

My world has nine deities, one for each alignment, but they are shaped by the thoughts, hopes and fears of their worshipers, so I plan to give them slightly different powers and personalities in their land and sea forms because aquatic people have different outlooks and priorities. Maybe I’ll make their underdark personalities different too. I think this will add character to my sea societies.

Some of my deities are gender flipping. I’m still working out the finer details. My land folk have a male moon god and female sun goddess and only one sea deity. The sea deity that the land folk think of as the goddess of the sea, to aquatic people is one of three see deity and in her case she is the sea deity that wants to strengthen ties between sea breathers an air breathers. That’s why the land folk think of her as the only sea deity. As far as sea folk are concerned, both the moon and sun are represented by male gods. They also view the three sea deities as the Three Daughters/Sisters of the Sea, and one of the sea goddesses is considered a male on land.

As far as the seafolk are concerned, there is Mother Sea and Father Sky. Life is made possible when Mother Sea and Father Sky join together. Father Sky provides “fire” to the sea by heating the waters and Mother Sea provides “water” to the sky by allowing evaporation.

My predatory Chaotic Evil deity, Maylar, is a male god on land and a female goddess in the sea. I figured the sea folk would view Maylar as a shark god and with most species of shark the female is larger and thicker skinned than the males on average.

I’m probably going to make my two sea floor deities males because I’m probably going to make them the patrons of crabs, and males tend to be larger than the females. That said, they are going to be minor gods, viewed as mere sidekicks to the Three Sisters of the Sea and Two Sons of the Father Sky.

I’m not sure if I’m going to give the aquatic people a god or goddess associated with land. As far as they are concerned, the landfolk are leeches or barnacles mooching off Father Sky and Mother Sea for their basic necessities.

So probably going with three sea goddesses, two sea floor gods, two sky gods, and two X-factors goddesses that travel between the realms.

I highly suggest this, because I'm not familiar with Rick Riordian and your description of deities doesn't entirely sound like your deities are entities that exist in the world. Mostly, if they have different powers, it would be because the sea and land peoples request they use different powers because of cultural reasons. If the gods act different, it's likely that either they have agreements "you handle X on land I handle in in the sea," or the landfolk have an easier time producing what god A wants before god A will agree to do X, while in the sea it's easier to produce the things god B wants before agreeing to do X.

Although with magic that lets you talk to a god, you can get very specific descriptions of how the god wants to be depicted and given; more specific than augury ect.. So if Maylar is treated as female in the sea and male on land, it may be because Maylar wants to be female in the sea and male on land. Or perhaps Maylar doesn't care either way (on this subject) but those are the traditions that arose from Maylar taking a shark form underwater and a lion form on land. Same for the other gods. Notably this means that if "the landfolk are leeches or barnacles mooching off Father Sky and Mother Sea," father sky and mother sea are either unable to prevent it or fine with it.

Also different in a game setting is that we can know the exact creature type of the things being negotiated with. So what the Romans treated identically to a god on a smaller scale, we can know is a fey/fiend/celestial/ect. This doesn't change that a leshy or kelp forest equivalent is still going to be treated about the same as a god in its local area though. Being able to tell a fey from a god doesn't step either from existing in the world or messing with your life.

[Scalenex]

So maybe a trickster or thief god?

That's a very good idea. I just need to figure out what he or she wants. I think trickster's are best where they have a driving goal or at least a broad philosophy.

Yeah, there isn't much underwater in d&d.

As long as you account for chewable forms making potions harder to administer to others. Otherwise, just make sure your table isn't just going to descend into jokes about tide pods.

We are now closer to 40 than 30. No tide pod references in this group.

That works. Simply replace my comments on copper and tin mining to refer to whatever alchemical material is being used.

You can use Gambesons instead of leather. Thick, quilted cloth does quite a bit at protecting the body.

Ceramics are usually brittle, which may or may not also take place in your setting. An excellent idea for arrows and bolts though, given trees are unlikely to grow underwater.

Ceramic bolts is a good idea. I'm still working on how crossbows and bows would work underwater. Spear guns and harpoon guns are very modern and would be hard to duplicate with medieval or quasi-medieval technology.

I highly suggest this, because I'm not familiar with Rick Riordian and your description of deities doesn't entirely sound like your deities are entities that exist in the world. Mostly, if they have different powers, it would be because the sea and land peoples request they use different powers because of cultural reasons. If the gods act different, it's likely that either they have agreements "you handle X on land I handle in in the sea," or the landfolk have an easier time producing what god A wants before god A will agree to do X, while in the sea it's easier to produce the things god B wants before agreeing to do X.

Although with magic that lets you talk to a god, you can get very specific descriptions of how the god wants to be depicted and given; more specific than augury ect.. So if Maylar is treated as female in the sea and male on land, it may be because Maylar wants to be female in the sea and male on land. Or perhaps Maylar doesn't care either way (on this subject) but those are the traditions that arose from Maylar taking a shark form underwater and a lion form on land. Same for the other gods. Notably this means that if "the landfolk are leeches or barnacles mooching off Father Sky and Mother Sea," father sky and mother sea are either unable to prevent it or fine with it.

I'm still working out the details. Even though the land and sea folk have technically the same gods, they have different myths for how the gods came to be.

The landfolk say that an evil god created the universe to feed off of it like a farmer raising souls. Then his nine lieutenants killed the tyrannical creator and stole his godly power.

The seafolk view the Sea, Sky, and to a lesser extant the Land as powerful cosmic forces. Maybe sentient but not sapient and capable of making conscious decisions. They sort of instinctual or accidentally spawned the nine gods and goddesses.

Also different in a game setting is that we can know the exact creature type of the things being negotiated with. So what the Romans treated identically to a god on a smaller scale, we can know is a fey/fiend/celestial/ect. This doesn't change that a leshy or kelp forest equivalent is still going to be treated about the same as a god in its local area though. Being able to tell a fey from a god doesn't step either from existing in the world or messing with your life.

I thought about that. I don't have a god for orcs and a god for dwarves and a god for elves and a god for Drow. All creatures have the same nine gods (with somewhat different interpretations, but still the same).

When a fey or some other powerful being leans heavily on an individual area and sort of gains a cult like following, they are nicknamed "Little gods."

[Mechalich]

Ceramic bolts is a good idea.

You need fire to make ceramics. You have to go on land to use fire. Ultimately this is the central problem. Without the ability to selectively heat items using fire the list of chemical transformations your civilization is capable of performing without magic is near zero. Undersea smelting using hydrothermal vents isn't an option because it takes more magic to make it work than simply artificially producing a bubble of air with fire in it does (or using magic to just go on land).

Any setting that is exclusively undersea is going to have incredibly strict limitations of technological attainment that tops out somewhere in the mid stone age or going to have to rely on magical explanations. However, there is little reason why your setting should be exclusively undersea unless it's something really weird like a subsurface ocean world. Otherwise even on a nominal 'water planet' there's likely to be at least a little land in the form of volcanic islands. The key questions therefore are: are your aquatic species at least partially amphibious and capable of conducting some land-based industries? or if not whether there's someone living on land who they can trade with for essentials.

Traditionally most D&D aquatic species have been at least partially amphibious and able to haul themselves out on land for some time ranging from days to permanently. They could therefore conduct industries requiring fire on land in such circumstances, though likely with more difficulty than terrestrial species. In particular, mining tends to take place in hot and dry subsurface environments that are brutal enough as it is (not for nothing was mining a traditional use of slaves and prisoners) which would be doubly excruciating for amphibious beings.

On the plus side, concentrated land-based industrial sites actually provides an undersea civilization with an excuse to actually be a civilization. Since you can't actually farm underwater - aside from some fairly limited things like shellfish production - or engage in traditional food storage, the fundamental basis for agricultural society found on land can't form. Without something like land-based industrial sites that concentrate populations and provide major advantages to those who hold them like metal weapons, your merfolk never develop past foraging bands. This is especially true given that the primary function behind building structures - shelter from the elements - simply doesn't apply in an underwater environment.

[Quizatzhaderac]

So on the surface we use container of water for lot of things (not just drinking), maybe containers of air are common (if not omnipresent). Used for food storage, fire-working, and keeping chemicals separated. Maybe add a low key magical means of acquiring air bubbles and keeping them in place. If some asses land-folk visit, it's nice that there happen to be these pockets of air around.

As for buildings: first, they need them for workshops that need air bubbles to do certain kinds of work. Second, safety; smaller communities need to me able to sleep without monsters eating you; larger communities need to be able to repel an army.

Jelly fish people
Based off the immortal jelly fish
Bad str and ex scores, good mental scores.

There is an important distinction between mental age and physical age. Physical age goes from zero to seven years. After one year the individual is physically mature. Mental maturity takes about as long as a human.

Every seven years they regress to child form, losing a small fraction of their memory. Personal memories are lost after a few decades. Technical memories last long, but will be entirely gone after a century of so if not relearned. They change one of their names each time they regress.

They can reproduce asexually by releasing a polyp. A polyp as more memory loss than a regression, but a polyp of a mental adult is also a mental adult.

Sexual reproduction is a bigger and rarer deal since the offspring will be mentally a child for it's first few life cycles.

[Mechalich]

So on the surface we use container of water for lot of things (not just drinking), maybe containers of air are common (if not omnipresent). Used for food storage, fire-working, and keeping chemicals separated. Maybe add a low key magical means of acquiring air bubbles and keeping them in place. If some asses land-folk visit, it's nice that there happen to be these pockets of air around.

There's a chicken and the egg problem involved with this. To have a container of air underwater it has to be airtight, but in order to make an airtight container you need at a minimum pottery, which you need fire to make. Additionally, once you open that container your air supply dissipates rapidly unless you've got a nearly airtight structure with appropriate pressure differentials (which requires nearly 20th century materials science). Bringing large amounts of air underwater to power your undersea civ using magic is basically a magitech solution. That's not a bad thing, necessarily, it just carries all the attendant baggage of magitech with it.

As for buildings: first, they need them for workshops that need air bubbles to do certain kinds of work. Second, safety; smaller communities need to me able to sleep without monsters eating you; larger communities need to be able to repel an army.

Unless you buildings are watertight and airtight you're not keeping air inside them for any significant period of time, and you can't even push the water out of a structure and replace it with air without some interesting pressure mitigation tricks in the first place, especially at any sort of significant depth (submarines, which are basically highly reinforced steel tubes with air inside, have crush depths that are actually surprisingly shallow).

You can ward off natural creatures without buildings, by using netting or other water-permeable barriers (or just by sleeping on land, if you can do that, works great for seals). This takes far less effort to enclose large areas and is in many ways much more effective since nets can trap and entangle large animals like whales that are more than capable of smashing through stonemasonry with ease. As for armies, well, first of all if your civilization development halts at the band or tribal level there just isn't any major warfare to speak of - there may be regular interpersonal conflicts (hunter gatherer societies have a shockingly high murder rate in many studies) and the occasional raid - but territorial warfare just doesn't happen because the resource stratification to support it doesn't exist. This is likely to be doubly true in the oceans, where due to shifting current patterns valuable territories will change locations in a far more dynamic fashion than they do on land.

Even if you do need fortifications, its important to recognize that undersea warfare is inherently three dimensional, which makes it pointless to build fortifications in anything resembling the fashion of their terrestrial analogues. Because you have to defend the entire surface of any structure you build against undermining and any portal is essentially equal access whether on the side or top of the building, defensive structures will probably be limited to squat bunkers atop hard substrates. Grand castles or even lovely domes are not defensible, especially not if they contain air - a glass dome city filled with air is almost impossibly vulnerable.

[Quizatzhaderac]

There's a chicken and the egg problem involved with this.

There's just so many ways out of chicken egg problems in a fantasy scenario. First of all: they presumably have contact with terrestrial and amphibious species. Second: they might have magic or non realistic materials. Third: the gods could have bootstrapped their civilization.

To have a container of air underwater it has to be airtight, but in order to make an airtight container you need at a minimum pottery, which you need fire to make. Additionally, once you open that container your air supply dissipates rapidly unless you've got a nearly airtight structure with appropriate pressure differentials (which requires nearly 20th century materials science). Bringing large amounts of air underwater to power your undersea civ using magic is basically a magitech solution. That's not a bad thing, necessarily, it just carries all the attendant baggage of magitech with it.

I think a desirable underwater setting is going to force some regular breaks with reality (even more-so than a regular fantasy setting). One of those things (that I think is a good trade off) is not having air bubbles behave correctly under massive pressure; namely that you can have an upside-down jar filled with air on the seafloor that isn't 200 times as dense as surface air and doesn't dissolve into the water.

You can ward off natural creatures without buildings, by using netting or other water-permeable barriers.

That's a fair point. But I would say the aesthetic goal is to have a visually noticeable village and not a patch of unmarked sea floor where the sea people sleep. Like a terrestrial village might be tents instead of proper buildings; a sea village might be "built" out of nets and sheets and the like.

if your civilization development halts at the band or tribal level

I would agree with you that presuming intelligent aquatic life we would likely only get tribal societies, but for building a fantasy setting, I think we're assuming civilizations.

Even if you do need fortifications, its important to recognize that undersea warfare is inherently three dimensional,

For an example, a city could be built as a pyramid. Limited entry points which are guarded and/or have gates. I suppose there would have to be some way to attack people patiently digging into the walls.

Outside the pyramid are multiple smaller detached buildings in a sort of slum. If an invading wanted to, it's could easily breech them, but it may not waste it's time on the least valuable part of the city.

Fictionalized materials

Air
Much higher bulk modulus than in our world; which means that a balloon taken to the sea floor won't collapse to a fraction of it's size. Air is also completely insoluble in water. Modern atomic theory is unknown and inapplicable. Air and water that are good for breathing contain low amounts of phlogiston, water and air that are bad for breathing have high amounts of it.

Quicksilver
Completely water insoluble and therefore not poisonous unless you actually directly swallow/breath some. Does not rust at all in the presence of ordinary water. Heavier than water, fluid, and dissolves metals.

Gallium
More common. Does not rust at all in the presence of ordinary water. Completely water insoluble. Can be worked by using body heat to melt it.

Oil
Completely water insoluble in the absence on an emulsifier. Some heavier than water varieties exist.

[Bohandas]

Before I reinvent the wheel, is there a very fluff heavy D&D source book developing the undersea biome in detail?

Stormwrack (3.5e) and The Sea Devils (2e) touch on this, although Stormwrack focuses more on boats and stuff, and Sea Devils is Sahugin specific

[Tom Kalbfus]

I believe merpeople can breath air, it's just that their bodies are not well designed for moving about on land. Aquatic elves have legs, so they can walk on land and do smithwork.

[KragBrightscale]

Regarding the construction of settlements underwater, traditional ideas for building on land would definitely be hard to achieve and not very effective.

I could see the mer-civilizations researching and applying methods of biology based techniques as alternatives to land based technology. Using the bones, scales, shells, etc of marine creatures as materials, or raising/manipulating other marine life into growing specific ways.

Settlements, villages or even cities could have coral based construction, use woven kelp as fabrics, airproof spaces using a special slime coating. Oversized barnacles on the back of huge ocean creatures could be used. Tunneling or digging into the sea floor or underwater ridges is also be possible. These settlements would likely form at defensible locations, such as in a gorge that is too narrow for the largest predators to enter, in shallower water so nothing could swim over it and structures could extend to the surface, hidden in a kelp forest. The largest cities might not fear anything aquatic, and build openly near major ocean currents.

Warfare would also be different as mentioned by others. 3 dimensional combat being the biggest difference.

This could result in generals creating special 3d formations like the cube, the spear, the maelstrom etc.

Ranged combat would be very difficult due to projectiles losing momentum quicker. A solution could be if traditional projectiles could be replaced with living projectiles, like Launching a volley of fish bred to resemble darts.

The taming and use of sea creatures would also be a key part of both warfare and society.

Armor could be quilted kelp as a base with scales bone, or the tough hide of some sea beasts. Although traditional leather working might be impossible, there could be underwater alternatives such as scrubbing and cleaning the hide before coating it in some kind of oil, or placing it in a mutated oyster for a week to process it, or leave it above a certain kind of vent that coats it in minerals. Weapons could be made in a similar fashion, if special minerals and ground up ore is placed in a giant oyster along with a form it could create a basic sword or trident. Basically using chemical reactions (compounds, ores, chemicals can all be made up) instead of high temperatures when forging.

Basically, It’s a fantasy setting, so I think undersea civilizations could make use of alternatives for any land based technology without needing to become completely magitech.

[Bohandas]

Also, construction of multi-story buildings would arguably be easier, due to bouyancy offsetting the weight of the materials

[PoeticallyPsyco]

First off, I'll second the recommendation for Stormwrack. It covers a lot of the biomes underwater and a lot of the various aquatic peoples.

-How do Mer-People get metal tools and weapons? Can they?

Aquatic people can acquire and work a type of metal called "pearlsteel", which is formed like a pearl in certain giant clams. It's also unusually light and flows through water unusually well, making even weapons that would be impractical underwater work a bit better (in 3.5, I also houserule that armor forged from it doesn't have its armor check penalty doubled while swimming). However, mostly they substitute bone, shells, and coral as building material. For a higher magic answer, "riverine" is an indestructible material made by sandwiching highly compressed water between (essentially) walls of force.

-Would Mer-People have to stick mostly to the ocean levels that get lots of sunlight? Would they mostly have to stick close to the sea floor? Would most Mer-People be nomadic?

Can't speak to nomadic or not, but I remember it's stated that even most aquatic peoples are terrified of what lurks in the dark abysses, to the point of refusing to wear armor heavy enough to cause them to sink should they be knocked unconscious. That said, I think I remember references to cities being on the ocean floor.

Oh, also, Aventi are definitely not nomadic, having a society very centralized around their sunken kingdom.


EDIT: One phenomenon I just remembered from Stormwrack is "airy water"; water with so much dissolved air in it that even landwalkers can breathe it. It would only take a little bit of handwaving to use that for typically air-requiring tasks like drying leather or maybe even full on smelting metal/firing clay.

[Stattick]

In DnD, magic is everywhere. It would be simple enough to say that most moderate to large sized settlements have areas of air within them. This facilitates trade with the outside world, either through direct trade, or through people using teleportation circles. You generally want to have some areas for air breathers to be able to survive, so you can facilitate trade, political negotiations, worship, and so forth. Some of these areas of air would likely also be dedicated to trades that require air - forging metals, glass and ceramics making, tanning leather (actually, just trade for it, leather making is horribly stinky work), and so forth.

For people living underwater, all of these types of activities and products would be exotic, thus highly valued. There'd likely be a range of other exotic services and products available there too. Cooked foods, smoked meats, fancy parties would be full of exotic scents (perfumes and incense), gauze clothing that drifts and shimmers in the air currents, luxuries that the sea would ruin (rugs, tapestries, paper with the printed word, painted canvas). You'd also find services impossible in the sea too, like the eerie beauty of terrestrial musical instruments. These areas would be where you'd find your decadent sea nobles.

Perhaps the industrial and luxurious areas would be water gaped from each other, to help insulate the nobles from the unpleasant smells of burning coal and the pounding of forges working metal.

These air pockets would have to be constantly tended. Priests of air and fire, and perhaps arcane magic wielders too, would take turns casting magics to freshen the air, the to increase its volume. These spells would likely have to be created for the setting, but they'd likely be relatively low level. Perhaps a cantrip would be sufficient to create enough air to fill a Leomund's Tiny Hut, or to merely freshen the air that's there. Domes of magical force may be sufficient to hold the sea at bay and keep the air within, perhaps permanized through magics long known to the sea, but forgotten on the land.

As far as alternate, magical industry, perhaps the sea elves or merefolk know how to create materials without even needing fire and air, singing ore into metal, and then metal into shape, and likewise their songs of forming can turn sand into glass and crystal. Or maybe it's the rituals of the priests that allow them the same capacity?

[brian 333]

Scrimshaw is the art of etching bone. Writing and magic scrolls could easily be done in scrimshaw, and tradeable art could be a kind of coinage if it is valued by surface cultures.

Sunfish Scale Armor
Sunfish are huge, and their large scales are very thick, tough, and light. Flexible waterproof armor of neutral buoyancy can be made of it.

Sharktooth Swords
A wooden or bone shaft grooved on either side with shark teeth set in the grooves and bound would make a deadly weapon. The Caribbean and Mesoamerican peoples used this technique to make obsidian swords. Longer shafts with smaller blades make spears, and spears with toggles make harpoons to prevent the thing you just killed from getting away.

Specially bred sponges, jellies, and sea cucumbers make excellent places to store potions.

Undersea forts would be stacked boulders with maze-like floor plans and trained moray eels and octopodes to guard the entrances. Those with land dweller contact or marine mammal friends will have air chambers.

[Nifft]

EDIT: One phenomenon I just remembered from Stormwrack is "airy water"; water with so much dissolved air in it that even landwalkers can breathe it. It would only take a little bit of handwaving to use that for typically air-requiring tasks like drying leather or maybe even full on smelting metal/firing clay.

Perhaps "airy water" spews forth from the Divine Bubbler, a deep copper pipe of unknown origin and unceasing function.

Perhaps these have been placed around the world at specific points of interest, often near some oddly realistic artificial seaweed and/or a fake shipwreck.

[brian 333]

Manta Ray Hide
+2 AC, Move (swim) 45 feet per round. Can breathe normally underwater without danger from water pressure, nitrogen narcosis, or the bends. Cannot make a 'run equivalent' move.
Cannot use handheld weapons while making use of the swim feature.

Sting Ray Hide
+1 AC. Move (swim) 30 feet. Can breathe as above. Can run. Cannot use hands while swimming.
Camouflage +6 while stationary on the sea floor.
Piercing melee attack, 5 foot reach, 1d8 +Str and other applicable bonuses. Can be used as a Sneak Attack.

These suits of armor resemble leather or hide armor when out of the water, but none of their special features work until the wearer enters the water.

Underwater the suit can give the wearer the ability to breathe water and can tramsform at the wearer's desire into the shape of an appropriate ray to allow the wearer to gain the swim and attack features. Held or carried items transform with the suit and are restored when the wearer reverts to humanoid form.
Spells with somatic components or with material components that must be manipulated can only be cast while in the character's humanoid form.

[sktarq]

Sunfish Scale Armor
Sunfish are huge, and their large scales are very thick, tough, and light. Flexible waterproof armor of neutral buoyancy can be made of it.

Firstly Sunfish in our world, don't have any scales. They have a very think hide covered in mucus and denticles... thick and tough sure but light it is not.
Honestly same idea could well be taken from a differently armoured fish.

Sharktooth Swords
A wooden or bone shaft grooved on either side with shark teeth set in the grooves and bound would make a deadly weapon. The Caribbean and Mesoamerican peoples used this technique to make obsidian swords. Longer shafts with smaller blades make spears, and spears with toggles make harpoons to prevent the thing you just killed from getting away.

eh. are swords even going to be a thing in underwater civ's? Swinging is HARD...making a sword is likely to be resource intensive...for what benefit? Harpoons (with barbs) make sense. Looking cool is something...but a pure status symbol.

Specially bred sponges, jellies, and sea cucumbers make excellent places to store potions.

Issue with this...they would pretty much have to be dead first.>> sponges don't "absorb" stuff like with think of them doing...That is basically filling up a combo of their lungs and GI tract as storage space.>>and once they are dead...how would they keep anything inside? The systems that work topside don't really work underwater...so fluid doesn't stick to them the same way... Echinoderms also wouldn't make great storage....you freak out a sea cucumber and you get covered in gets...and high velocity movement, pressure changes, being grabbed, would all be a good way to set it off. So corpses then....May actually have some luck with certain kinds of snails as well...the kind that can seal their shells-if the part of the body that holds the seal to the shell....rest of the body could rot...you all this no matter what sounds like LOTS of work.
or just refill a mermaids purse and seal with some glue like material-seems like far less work and far less flinstones-under-the-sea with a the feeding, storage, etc problems that brings with it.

EDIT: okay the more I think about it. metal, have to use pseudo-bio-engineering mostly for invertebrates ...this has already been done. The Thri-Keen. Snails that lay down a plastic like material in order to build for example. So I'd start digging in various Darksun Splatbooks (I know there is a 2e one that goes into this in detail but their may be more...use google)

[brian 333]

Sunfish technically have scutes which are laminated scale and bone. They grow differently from scales, but serve the same purpose.

A stabbing, slashing sword would work fine underwater. You aren't going to be swinging or chopping, but in close quarters melee having a weapon you can use to slice or block your opponent's weapon might be handy.

In any case, the idea is to present ideas. Don't use the ones you don't like.

Megadont Dagger
The tooth of a giant shark has had a hole carved into its base which has been fitted to the hand, creating a punch dagger. Military versions have a supporting wrist grip which can be lashed to the forearm.

[brian 333]

The surf cresting over the Archgpelago Reef made a rythmic booming which could be felt in the deep water as the hunters returned. Nets filled with crabs and oysters and buoyed with gas bladders were being towed by the mermen as they ascended the nearly vertical wall which separated the city of coral from the dark abyss.

Reech sang a song as the party approached a crevice in the wall. Booly reached out with her sinuous coils and drew her head out far enough to see them. The color patterns on her skin shifted quickly in flowing white stripes and grey dots on a white background.

"Yes, we have something for you today," Reech sang while Toong and Chuure offered a heavy net to the octopus. She opened the net with three tentacle tips as two other arms slid into the net to secure the giant oyster. With her prize in hand she pulsed yellow and black as she jetted into the recess in the coral wall.

The party continued up the wall led by Chuure who was releasing air from the bladder attached to the now empty net.

The fissure became a gap, then a narrow gully between the crowns of two reefs. The booming surf was louder here, but the main challenge was to guide the full nets between narrow coral walls as the rising tide drew the hunters in, (just as the ebb tide had pushed them out six hours earlier.)

Reef sharks patrolled the channel and showed curiosity, but they were night hunters. Their daylight curiosity would become ferocity in the dark unless one knew the calming song Reech was singing.

And then the song was answered from ahead. As the party passed the outer margin of the reef the ferocity of the surf waned and though the current still rushed inward the rythmic crash of water faded to background sound. Ahead other singers joined the first, and others of the hunters took up Reech's tune.

Almost without warning the canyon through the reef, (and its tidal current,) ended in the central lagoon. In the walls around the lagoon were the homes and shops of the city, sculpted in stone and cultured coral.

The singers and hunters merged; mermen, mermaids, and merkids, cheerfully greeted one another as the group made their way to the city's larder in the center of the lagoon.

[Stattick]

I'd like to see some Cecaelia & other hybrids between humanoids and sea creatures.

[Yanagi]

-What do Mer-people use for pen and paper? If they don't have a better substitute that clay tablets, is literacy basically unheard of.

Okay, so the cheat answer is: handwave that there's some of piscine or sea-mammal vellum that doesn't break down in salt water, and ditto for ink. Or there's a waterproofing spell.

More elaborate...the ocean surface becomes a region for specialized forms of labor where air and sunlight are beneficial, and part of this labor sector is paper-making, binding, and scribework. Near-surface buildings...or anchored barges...serve as libraries and storage facilities for volumes and collections. In this case, part of social position within Sea Rome is how much right an individual has to study written language and travel to engage with longer, more complex documents and written materials.

It could be that many folks are illiterate or only communicate with a sets of ideograms or pictographs that can be scratched into resistant surfaces like shells or bone. Or it could be that this system is highly sophisticated...equivalent to Chinese writing or cuneiform...with a set of standards strokes and radicals used in different combinations to create ideograms with very complex meanings, and the gradient within society is how deep their vocabulary of ideograms is.

However...ever heard of quipu?

It's a Andean method of recording information in long sequences of knotted, colored thread.

Written language is an abstract representation of sounds, but it isn't necessary that the abstraction of a phoneme be a character inscribed on a page.

So a possibility is that undersea folks encode their information in an entirely different coding system, like arrays of tiny colored beads, or knotted fibers, or arranging florescent corals into patterns. or by piercing a semi-rigid medium with larger and smaller boring devices (kind of like Morse code) to create something that could be read by touch and sight. Or all of the above, since groups in littoral waters with light would have different needs and resources than groups in abyssal conditions.

-How do aquatic adventurers use magic scrolls and potions?

Potions are made with something that is immiscible with water, like oil. Or made into something equivalent to a gummy--agar and carrageenan from seaweed being available to create thick gels--that doesn't immediately diffuse when exposed to water.

Scrolls follow from what I said about books: they're an encoding of information, they medium isn't actually constrained. So a scroll could be and incredibly delicate etched scallop shell that snaps into fragments after casting, or a string of beads that breaks apart when used up.

-How do Mer-People talk? Can they talk like land people with minimal fuss or do they do need hand signals or something exotic like telepathy or electrical currents to speak?

All of the above?

Again, this probably shouldn't be uniform if you're going to have many undersea sapients from different conditions...and squids and crabs and sharks have radically different mouth parts.

Look, it's probably easiest if the basic mer-people use speech. But since water carries sound so effectively it may be that they also use hand gestures (or whole-body gestures and movements) both to say quiet for safety reasons and for personal privacy reasons.

Since sharks have ampullae of Lorenzini, the idea that they would talk to each other at least in part through electrical currents is interesting. I particularly like that this makes them potentially aloof from other sea critters, able to convey information through a means that just doesn't translate, and is also exceedingly odd to witness without context. Especially when combined with magic, because the idea of speaking at great length, point-to-point by sending out a jolt of electricity is just cool.

Given the radically different body types, if there was to be a common spoken language it might have to be artificially constructed, selecting sounds that every creature type could make or learn to make. And not necessary with mouths: learning to make distinct clicks and pops with claws, tentacles, beaks/mouth parts is a possibility. Another possibility would be a muscial language, like how Bata drums can be used to speak Lukumi--for all the different creatures to speak to one another, there's literally an instrument that can create distinct sounds that are the equivalent of phoneme set.

-How do Mer-People get metal tools and weapons? Can they?

The answer to this question hinges on a lot of different things that are ultimately your choice:

- Do you want metal to be rare or common?
- Is it available as a trade item within the underwater cultural system or in exchanges with land-dwellers? How about as a scavenged or stolen item from land-dwellers?
- Does metal have use-value, or does it also have prestige-value?
- In the setting re there magical means of creating metal, or magical metals that can be obtained through means other than conventional smelting?
- Are there magical materials that can function equivalent to metal, such as exceptionally-good stone or obsidian?
- If there are an abundance of monstrous sea creatures, how will harvested resources from those creatures increase the variety and adaptability of harvesting "natural" materials beyond what natural materials (such as shark teeth, or stingray tails) are capable of in real life?
- In these seafolk societies, what does metal mean, particularly if metal can only be obtained from dry land resources?

Consider:

Metal making could be a simultaneously taboo but important social role, where certain clans or individuals go onto land and make metal from ores they've learned to process. This is not just a job, it's a kind of ritualized transgressive act that has complicated significance for a society that is afraid of dry land. To be a smith is like being a medicine worker or other ritual: you become liminal to your society, touched by a mystery, even as you perform a necessary societal function. What they create from metal is not circulated within a normal market system, but is instead part of a sacred...or just prestigious...exchange system: it means something to be given a metal ornament, or granted a metal weapon.

Conversely, metal could be seen as useful, but an unpleasant intrusion of land-dwellers. Scavenging nails and rivets from sunken ships and using them as substitutes for other materials could be an opportunistic behavior that's also seen as poor taste, or even as some kind of taboo that requires a compensating act fo purification or penance. Some people might see trading for metal as degrading, but capturing metal as a kind of counting coup.

Now, as a person who loves deep sea stuff, I rather like the idea that there's a legendary material that's...metal smelted and forged at an abyssal thermal vent. I can't justify this as realistic in any way, but I think it would be cool and in keeping with the mythic themes of magical metals created in unusual circumstances.

I also think you should give a hard think about what kind of sea monsters/magic critters are around, and available to be harvested and processed to make stuff. I mean, monster ecology never makes sense, but if there are kinds of critters that are more common, then they're likely to have bits--bones, teeth, scale, hide, etc--that find their way into the technology of sea dwellers. And this is a thing that would also be distinct by depth: big sea monsters dying and dropping into the abyssal zone to be picked apart--equivalent to what happens to whales--would be bonanzas.

-Would Mer-People have to stick mostly to the ocean levels that get lots of sunlight? Would they mostly have to stick close to the sea floor? Would most Mer-People be nomadic?

There's no right answer, but the closest thing I can offer to a structure for an answer is:

It all depends on if you want places with full-time residents and greater population density. The more of each there is, the more there has to be a system to feed those people.

If you look at ocean documentaries like Blue Planet the underwater world is very roughly divide-able by depth and proximity to land. Coastal regions--estuaries, marshes, reefs--and relatively shallow regions tend to have dense biomass and great biodiversity packed into small spaces. Open seas tend to be more thinly populated, the equivalent of great grass plains or deserts. The depths are a space unto themselves with specialized creatures that hunt one another in the dark and a calorie economy that often starts with marine snow--biomass detritus falling from above.

Mer-people attempting to form a culture are going to dwell where there are enough calories to sustain them--and ideally with as little work as possible per calorie--but in different locations different mer-people groups might adopt different successful strategies to subsist. In a Sea Rome, there would likely be many different Mer-people cultures with different food and living strategies.

Foraging would work exactly like on land: gather sea-weed, molluscs, etc...hunt fish. In resource-rich regions like around salt mangroves this could be a fairly easy life--maybe not completely sedentary but with a smaller cyclical movement between forage sites--but there could also be far-travelling, ocean-crossing foragers that leaned heavy into hunting big game, equivalent to North Americans who followed the buffalo or Asian steppe nomads moving with mustang herds.

Except in absolutely ideal conditions, though, fully sedentary living and permanent settlements mean bio-manipulation: taking control of available wild resources to increase calorie yield. When this happens long enough, you end up with domesticated species and the two survival strategies associated with domesticated species: agriculture and pastoralism. To have Sea Rome--an empire with the dual logistical needs of feeding moving armies and stationary city populations--you've got to have very sophisticated, developed agriculture and pastoralism, meaning that not only have things been domesticated, but many, many rounds of breeding and transplantation have created shared, well-understood food systems that can be transplanted from locations to location.

I don't entirely know what that would look like in a setting that is (1) underwater in an ocean, (2) has a fantasy ecology, but the basics could be inferred from how real-life sea resources tend to be worked:

• Seaweeds are comparatively easy to propagate and tend and there are many edible varieties, and in a "civilized" area where multiple populations have exchanged seeds/plants to expand their food systems, it is likely that there is a predominant type that grows most places, with good yield (the equivalent or wheat/barley, or maize); but also other varieties grown because they are adapted to specific conditions (the equivalent of rye cultivation in cold climates) or because they provide specific nutrients and/or flavors (the equivalent of vegetables). I don't know my sea vegetables very well, but if sea-dwellers had access to beaches or shoals there might be other halophile plants they could cultivate like crithmum, or there might be edible aquatic plants like Nelumbo lotuses or katniss, that became salt-adapted.
  
  
• Open water nomads might incorporate seaweed rafts into their travel cycles, as a sustainable nutrition source and as a lure for wild fish. Another potential niche for open-water nomads is to move across open spaces in a way similar to Polynesian settlers of the Pacific islands: wayfinding from one small island coastal region to the next, taking along the equivalent of canoe plants to subsist on.
  
  
• There are a lot of underwater animals that could be farmed, who life cycle contains very little need for movement or space...only sufficient nutrition and oxygenation. In coastal regions, things like clams and oysters--indeed, pretty much all your molluscs plus crustaceans like shrimp--would be easy to farm, though each type would have conditions (depth, available oxygen) that kept them from being common ocean-wide. Hearty species that adapted well, like zebra muscles, would become staple foods.
  
  
• Opportunistic eaters like crabs and eels--things that can survive and fatten up on scrap--would become the equivalent of pigs. Meat animals equivalent to cows that could eat some inedible biomass--plankton, mangrove greens--could be the basis of a sea equivalent to the pastoral niche (like the Dinka, or the Mongols), though I can't imagine there'd be an underwater equivalent of dairy.
  
  
• I don't know if fish can truly be domesticated, but mer-pastoralism is an idea that should be entertained. For example, merfolk might have mutualism with various sea mammals...wide ocean merfolk with large cetaceans, reef merfolk with dolphins and seals and such. Since shark folk (in my take) have a unique ability to transmit electrical impulses, it may be that this gives them a unique ability to control manage open-water fish shoals and effectively treat them as herds.
  
  
• The lightless depths would be the leanest places, and also have an entirely different food system from everywhere else. Marine snow...and chemometabolic creatures like vent bacteria?...and the occasional megafauna carcass would be the basis of the food systems. Your foragable and farmable options would be things like crabs, vent worms, hagfish, the various sole-like bottom feeders. It would be an entirely different menu than other regions. I rather like the idea of the bottom dwellers becoming megafauna hunters--baiting and killing whales and other big sea critters, but I also like the idea of bottom dwellers creating manifolds to channel heat and gas from thermal vents to create huge hothouses of vent worms and albino crabs.

So in the world you're describing there would likely be both sedentary people and nomads, and the nomads would be split between far-traveling pastoral types, and less-travelling foraging types...barring an imperial force attempting to settle and standardize how land was used. Coastal regions would be the equivalent of nice fertile river valleys, reefs would be like managed forests. Because of seaweed cultivation and stuff like artificial reefs it's likely the surface, even in a city, would be zoned for agriculture. Open water would be either like managed pasture or the open steppe...and chances are good that nomads following or controlling shoals/pods/herds would have the same kind of understanding of usage rights and possession of critical locations that, say, camel herders in the Arabian Desert do. The abyssal regions would be entirely on a different system than everyone else, working with entirely different environmentally assets, such that I can't even come up with a cultural analogue.

[Dagda Mor]

What's the underwater equivalent of 1: herding, and 2: agriculture?

In other words, establishing and maintaining an optimal food supply, such that people in your civilization have a surplus of food and can afford to have a percentage of the populace spend a percentage of their time doing other things.