Bottom of the Sea for Early Adventurers

[Parvum]

I expressed to my group that I wanted to try a 5th edition game, and had started work on a campaign. Since the campaign we were in was coming close to wrapping up, I thought I might like the chance to take the DM seat and try out this idea that's been buzzing around in my head.
Today I found out that I could have my chance... in two weeks, to run roughly four sessions.
So I need as much as you can give me on 5th edition at the bottom of the ocean for early level adventurers, in their first few levels. Underwater magic items, mundane items, low CR miscellaneous creatures, more in depth rules for being more in the depths, and even anything to help make this unlikely setting a bit more immersive. Ways to make the setting still feel familiar enough that the players aren't alienated and distanced, but still feel like an underwater adventure. Official content or your own homebrew creations and house rules, I'll take it all.

UPDATE: Pushed back indefinitely, so I'm no longer in a rush to put it all together. But I'd still like anyone's ideas on how to personalize an ocean floor campaign.

[RickAllison]

I'll start with creatures, because that's the only part I can really think of off the top of my head.

Shallow Water:
Crab (CR 0)
Giant Crab (CR 1/8)


Both/Middle:
Giant Octopus (CR 1)
Giant Sea Horse (CR 1/2)
Giant Shark (CR 5)
Hunter Shark (CR 2)
Killer Whale (CR 3)
Octopus (CR 0)
Quipper (might be more freshwater, your call I suppose; CR 0)
Reef Shark (CR 1/2)
Sea Horse (CR 0)
Swarm of Quippers (CR 1)
Sahuagin (base, 1/2; Priestess, 2; Baron, 5)
Merrow (CR 2)
Merfolk (CR 1/8)
Kuo-Toa (various, CR 1/4-6)
Marid (CR 11)

Deep Water:
Kraken (CR 23)
Sea Hag (CR 2)
Dragon Turtle (CR 17)
Chuul (CR 4, great for Cthullhu-esque horror!)
Aboleth (CR 10)

That should give plenty! I can give more information if desired.

EDIT: For a little bit more in-depth, Merfolk are your go-to non-hostile characters. They are TN and so great for creating the feel of civilization where the party can rest, but not rely on hospitality. Individual Quipper are fantastic for driving the players on because they are themselves weak, but the harassing nature of them (getting advantage on injured targets) encourages the party to move on before the swarm arrives. Obviously, Kraken, Marids, and Aboleths are fantastic BBEGs, and the Dragon Turtle can be a fun mechanic where two parties vie to gain the loyalty of the giant lug.

[EvanescentHero]

Underwater magic items, mundane items, low CR miscellaneous creatures, more in depth rules for being more in the depths, and even anything to help make this unlikely setting a bit more immersive.

I see what you did there.

That being said, early levels underwater seems tough, since I feel like underwater is a setting they expect you to encounter later in a campaign. A lot of the cooler aquatic monsters are higher CRs than would be appropriate...

One magic item that I feel an aquatic campaign needs is the Apparatus of Kawalish though.

[Laserlight]

We had an aquatic game, with discussion of underwater combat (http://www.giantitp.com/forums/showthread.php?319236-Underwater-Combat-changes-need-input). It was 4th Edition, but some of it will still be applicable.

[RickAllison]

Page 116 of the DMG and the next few more and page 198 of the PHB will be your friends. Page 305 of the DMG has a handy list of various enemies, so that could be useful.
For magic items, Potions of Water Breathing, Cap of Water Breathing, the Apparatus of Kawalish (as mentioned by an above poster), Cloak of the Manta Ray, Dust of Dryness (I like the idea of someone using it as a weapon like a depth charge :smallbiggrin:), Mariner's Armor, Ring of Water Elemental Command (might be too high of difficulty to get the full use of it, however), Wave (not for the PCs, more for a powerful NPC :smallwink:).

[unwise]

So are the PCs aquatic? Or gasping desperately for air and being crushed by the pressure? Are they magically transported there, or native to there?

[Celcey]

So are the PCs aquatic? Or gasping desperately for air and being crushed by the pressure? Are they magically transported there, or native to there?

Definitely important questions to answer. Earlier additions may already have some more stuff suited to aquatic adventure, so definitely see if your players would be interested in making their own home brew or conventions, and for sure look in the home brew section.

However, for any character who's a non aquatic race, I would give them a non-steal-able phlebotinum (someyhing that refuses to be removed and can't fall off) to handwave all of the problems of not being able to breath, water pressure, and give them a swimming speed. Unless having to deal with finding and keeping those things is something you'd want to use as a plot device, of course (the merfolk will give you that information you need... In exchange for that lovely hat).

I would also recommend starting at level 3, since your players are experienced enough to do so. That way you get a little bit of the fun of powers, and everyone gets their subclass, plus you have a bit more variety in the monsters you can use, especially since your underwater options are limited in the first place.

Asides from the GitP home brew section, I would also recommend this thread on Reddit: https://www.reddit.com/r/monsteraday

While I've never personally perused it myself, it comes highly recommended from one of my players, and there may be some cool aquatic monsters for you to use.

Best of luck to you, and let us know how the adventure goes!

[Shining Wrath]

Also, there's no light down there naturally. There's more light on the dark side of the moon than at the bottom of the ocean. If your characters lack darkvision they'll need glow globes or something along those lines that works underwater.

Make sure your characters know they are going to be doing Voyage to the Bottom of the Sea prior to character creation. I'd hate to be a fire-based draconic sorcerer in a world where every target is resistant to fire damage.

[Parvum]

So are the PCs aquatic? Or gasping desperately for air and being crushed by the pressure? Are they magically transported there, or native to there?

Aquatic PCs, aquatic races, snatched from adapted MM races and from various corners of the internet.

So obvious changes would be air-breathing items, and other minor changes. I'm thinking of increasing the spell level of Control Water, and making a single target version of Water Walk that works on enemies (I wholeheartedly recommend looking up what Water Walk does underwater). But there are less obvious things, especially in the rules. Do effects that knock people prone matter? Should there be underwater-specific conditions? What about heavy armour? I've got an idea about heavy armour sinking characters on their turn unless they spend an amount of movement, unless they begin their turn on the ocean floor or a solid surface. That's about it, though.

[EvanescentHero]

I'm thinking of increasing the spell level of Control Water, and making a single target version of Water Walk that works on enemies (I wholeheartedly recommend looking up what Water Walk does underwater).

Ha, that's pretty good. What kind of save are you thinking for that spell?