Making an Underwater city with effort.

[Zmeoaice]

I've been thinking of making a fantasy story about Mermaids, and am trying to design the world they live in. It's going to be vaguely middle ages, with tons of anachronism.

Anyhow I'd like the city to accommodate our fishy friends as well as show the reality of the physics of the situation. If there are any movies or tv shows which portray an underwater city (One that is completely in the water, not in a dome) realisticly (no Spongebob) I'd appreciate it.

Some things I'd like to know would be whether you can smelt metal or create glass underwater in a furnace, or whether it would either cool too fast or the convection of the water would burn anyone who tries.

Another thing would be if it's possible to ride currents like sailing a ship.

This is fiction so not everything has to be accurate but I'm trying to adapt a city underwater as realistic as possibly

[Khedrac]

For depictions of what it could be like, you could do worse than start with Disney's The Little Mermaid. From what I rememebr (it's been a long time) the palace at the start is pretty much what you want.

As for smelting (and glass) I think the problem is that water is too good at convection - e.g. if you get close enough to a geothermal vent to get the heat you want, then you will be too hot to survive yourelf.

I think you should be able to ride the underwater currents, but they would be pretty slow.

[Draconi Redfir]

Stairs would of course be all but nonexistant. many homes would likely contain mere pipes to different floors. if you wanted to go up a floor, you just go to this pipe and swim up a bit.

Alternatively a more organic feel could also be interesting, there are no clear "floors" to the home, as every roof and "ground" is littered with one or more holes in various asyumetrical places. So you kind of swim through a web of rooms ascending or descending whenever you reach the room/floor you want.

As for smelting... Perhaps there could be some way where the smith didn't need to be around it 24/7? Perhaps there is a plant or an animal that lives near a geothermal vent that is strong enough to hold molten metal in it, and the vent only activates for a breif period of time every so often. So the Smiths place some metal in the plant/animal, leave it over or near the vent, and as the metal melts, it somehow pours into a mold or a cast that is either on the ground next too, or also inside the organism to allow it to settle into the shape the smith wants. From there the smith waits for the water to cool, rushes in, grabs the mold, then works it a little more while it's cooler (maybe still a bit warm) before putting it back to heat up again before repeating the process. This way the mermaid never has to be directly close to the heat to begin with.

[Traab]

Forget smelting ore, go a step beyond reality when it comes to fabrics. After all, we already have kevlar, we have things like say, spider silk that has the tensile strength of steel and a 6th the density, working from there your merpeople could have developed things like plant fiber weaves as strong as bridge support cables with cloth armor stronger than plate mail. They could have homes built from stone and plant life, make it pretty with mother of pearl sheathing for accents and designs since paint would be kinda hard to work with.

[Leewei]

Smelting would be problematic. Slags and toxic fumes are manageable in a well-ventilated gas medium. Water is a great solvent. It's likely creatures working with hot ores would be exposed to a lot of toxicity (on top of incredible heat due to thermal contact).

The best solution would be a furnace built at the surface of the ocean, with slag from ore processing getting dumped into a powerful current leading somewhere unimportant to the sea folk.

Mining itself would be horrendous and toxic for the same reason. As before, using a powerful current to sweep away pollutants looks like the best approach.

[tomandtish]

I've been thinking of making a fantasy story about Mermaids, and am trying to design the world they live in. It's going to be vaguely middle ages, with tons of anachronism.

Anyhow I'd like the city to accommodate our fishy friends as well as show the reality of the physics of the situation. If there are any movies or tv shows which portray an underwater city (One that is completely in the water, not in a dome) realisticly (no Spongebob) I'd appreciate it.

Almost no show/movie depicts underwater cities realistically, because they don't want to jeopardize the compromise of merfolk being shallow water creatures or deep water creatures. They also almost never acknowledge whether merfolk are mammals or fish. A LOT is going to depend on whether young are born live or from eggs....

Shallow water fish have open swim bladders (they adjust buoyancy by breathing air directly). Common among freshwater fish but you'll see it among some very shallow dwelling salt water fish. Assuming your merfolk can even breath air directly at all, this is the more likely scenario. Shallow towns/etc. with easy access to the surface. Advabtages: Can recharge bladder in one gulp. Disadvantage: If not at surface, can't recharge at all.

Deep water fish have closed swim bladders (they can't fill them by breathing air directly and have specialized capillaries that handle the function). Advantage: they can always recharge. Disdvantage: It's a slower process (so an extended chase might cause problems).

There's also the cartilage based life, which usually doesn't have swim bladders at all (sharks for example). They combine light skeletons with constant movement to maintain buoyancy (although the movement can be so slight as to be almost invisible).

Merfolk who live in the deeps (100s to 1000s of feet down) would almost never come to the surface and would be at a big disadvantage there. If your merfolk live in the shallows, the deeps would be the equivalent of diving for us, requiring equipment.



Some things I'd like to know would be whether you can smelt metal or create glass underwater in a furnace, or whether it would either cool too fast or the convection of the water would burn anyone who tries.

Excluding magic (and you can assume this applies to everything here), you probably can't smelt directly underwater. However, there are such things as underwater air-filled caves, and an intelligent race could certainly create them. For merfolk it would be a specialized room (and possibly more hazardous than the land-based equivalent since you might have to access it in a "wet suit").


Another thing would be if it's possible to ride currents like sailing a ship.

This is fiction so not everything has to be accurate but I'm trying to adapt a city underwater as realistic as possibly

Semantic point here. If you are just following an existing current you are arguably drifting, not sailing (even if you are using rudders to cut back and forth across the current). Sailing is using an air current to counter the forces on the hull of your vessel (usually those imparted by the water such as water current).

(Sorry, but I read that and immediately heard my father and grandfather screaming. They were avid sailors and I had to silence the voices)... :smallwink:

Drifting is absolutely possible. Even today submarines have been known to do it. For actual sailing, you'd have to devise a system to catch one water current with a "sail" and use it to move your vessel while at least part of the body is outside that water current (or in another one).

I'm working on memory here and am on my phone, so if I get some of this wrong I apologize.

The Gulf Stream is about 60 miles wide and ranges from 1/2 to 3/4 miles deep. It moves about 5 1/2 miles per hour. So note that ocean currents might only be used for assistance. I'm working on memory, but I believe the fastest ocean current is only around 6.5 miles per hour (and deep water tend to be slower than shallow). So currents are probably more likely to provide an "assist" rather than be the main force for transportation. I assume that even with rest time most merfolk can cover far more in a day swimming on their own than anyone could "sailing" the currents.

But back to the earlier point: The biggest thing to decide is if they are deep water or shallow water dwellers, and then plan accordingly, noting that encounters in the other environment would be exceedingly rare.

[Giggling Ghast]

I think any sentient underwater race would look more like sahaugin than mermaids. I would guess they would have natural defences like sharp bone ridges and poison fangs/stingers.

And in all likelihood, wouldn't they have to be carnivorous? What I know about marine plant life could fill a thimble; perhaps marine agriculture is totally viable for a species that can survive in the ocean. But the only underwater "crop" I've heard of people farming is seaweed, and I can't imagine an entire civilization surviving on it.

EDIT: Amusingly, Buzzfeed did an article on what Ariel would look like if she evolved in different environments. Maybe you'll find it informative, as it does bring up an interesting point: you have to consider what type of ocean environment your civilization is located in. (It does confirm my suspicion that deep sea merfolk would have to be carnivorous.)

https://www.buzzfeed.com/clairedelouraille/ariel-reimagined?utm_term=.sq5r3lmkPp#.qb102MWKJk

[Zmeoaice]

Another thing I would like to figure out is how writing would work. They could probably weave

There are people on the surface who have interacted with the Mermaids.


Almost no show/movie depicts underwater cities realistically, because they don't want to jeopardize the compromise of merfolk being shallow water creatures or deep water creatures. They also almost never acknowledge whether merfolk are mammals or fish. A LOT is going to depend on whether young are born live or from eggs....

Most merfolk will come from eggs, though Shark based Merfolk might be a bit different.

There will be at least two sentient species, but I'm not sure how many I should put. The Octopus-people will be a different species, and all Bony Fish are the same species, with sharks and rays possibly being a different one.


Merfolk who live in the deeps (100s to 1000s of feet down) would almost never come to the surface and would be at a big disadvantage there. If your merfolk live in the shallows, the deeps would be the equivalent of diving for us, requiring equipment.

Most of the will probably have designs similar to the deep water fish, however given that they farm Kelp which can only grow with Sunlight, they would probably have a shallow water biology. Especially if I decide they use a furnace above water. Though I suppose I could give them the best of both worlds and have a self-filling swim bladder which can be filled quicker with a gulp of air.


I think any sentient underwater race would look more like sahaugin than mermaids. I would guess they would have natural defences like sharp bone ridges and poison fangs/stingers.

The merfolk will be somewhat more fish than how they're often portrayed in media. They'll still have human faces and general torso shape, but they will be colored the way the fish are rather than have flesh colored skin, no mammaries, fins for ears, some have fins on their arms. A few will have stingers like the one based on a lionfish, and one based on a stingray.


And in all likelihood, wouldn't they have to be carnivorous? What I know about marine plant life could fill a thimble; perhaps marine agriculture is totally viable for a species that can survive in the ocean. But the only underwater "crop" I've heard of people farming is seaweed, and I can't imagine an entire civilization surviving on it.

They'll be omnivores, raising both livestock and sea plants. Manatees will be their "beef", but they'll also raise fish and crustaceans. Hunting isn't out of the question either. Dolphins and Hippocampi are domesticated but not eaten.

Many sea animals will have more in common with the land animal they're named after

Manatee (Sea Cow), Dogfish, Parrotfish, Catfish, Eagle Ray, Sea Hare, ect

Kelp will be grown, but I could create fictional sea vegetation.

[Cespenar]

Another thing I would like to figure out is how writing would work. They could probably weave

Go wild. Maybe they write in 3D, using the secretions of a type of crab or something to calcify sand.

[Durkoala]

Another thing I would like to figure out is how writing would work. They could probably weave. there's also the roman/greek option of writing on tablets of wax. lesser writings would be erased and reused, but important things could be preserved by coating the tablet with a harder covering. Very important things would probably be carved into stone.

There's also the Quipu (https://en.wikipedia.org/wiki/Quipu), incan knot language where information was "written" as various types of knots in strings.



They'll be omnivores, raising both livestock and sea plants. Manatees will be their "beef", but they'll also raise fish and crustaceans. Hunting isn't out of the question either. Dolphins and Hippocampi are domesticated but not eaten.

Many sea animals will have more in common with the land animal they're named after

Manatee (Sea Cow), Dogfish, Parrotfish, Catfish, Eagle Ray, Sea Hare, ect

Kelp will be grown, but I could create fictional sea vegetation.

How do they keep their flocks from swimming away? It's probably not easy to have a space large enough to keep a school of fish healthy while also being secure enough to hold them. Perhaps a coral atoll that has been built on to seal it up?

[hamishspence]

Maybe have herders who follow the herd of fish around - protecting them from predators, but also killing them themselves and sending the meat back to the cities?

[Kislath]

I don't get why you're so concerned about a furnace & smelting.
However, I can see two ways around it.

1-- build a wall around a lava vent. Cool water flows around the vent outside the wall, and the blacksmith can open up a little slot to put things inside the vent to heat them up without cooking himself. For that matter, a lot of hot water would be shooting out of the top of the chimney, so maybe that could be useful.

2-- make things out of pearl instead of metal. Make molds/templates/pre-forms of things, and put them into giant clams. The clams cover them in nacre, making pearly analogs of things you'd normally make out of iron.

[Legato Endless]

If it's set in the ocean, something to take account architecturally is Seafood spreading (https://en.m.wikipedia.org/wiki/Seafloor_spreading).

[tantric]

watch "Mermaids: the Body Found" from animal planet. sample:


https://www.youtube.com/watch?v=gNey8YT1yHo

nodules of manganese and iron are found on the seafloor, which would require no smelting.