This would probably be a part of some sea off in a location that is sort of lacking islands, like the top left of the Bronze Sea. Would be static and not some random spawning thing, this is it’s own location.
so basically each layer would internally be a separate location.
a few things are:
Upper Depths would have some passive things like sea snails and crabs that just move around slowly on some of the clams sticking out.
since it still is past the bottom of the sea chests would be abundant in Upper Depths
Lower Depths eels have holes in the sides that are their nests, they snap out of them if you get too close
Lower Depths undersea volcanos release damaging steam and have tier 2+ chests on them, decently abundant. The area itself would be very warm on the temperature meter because of the volcanos
Midnight Point would have some of those weird jellyfish you’d see if you google “Mariana Trench Jellyfish” and near the top would contain a hypothetical tier 3 waterbreathing reagent in decent abundance, and near Point Thalass would have a very, very high abundance of tier 3 chests.
Point Thalass would have nothing apart from a special untradable hat at the very, very bottom on a tiny spire that gives a badge as well as the hat, being a reward for making it. The walls as mentioned are specially jagged to provide for the ability to regenerate stamina as unlike other levels doesn’t have any outcrops or other stuff jutting out the walls to regen stamina. Your Air Drain would probably have a flat bonus added on regardless of waterbreathing and other stuff from the sheer depth
Below is a super smooth wall that has an incline, basically meaning death since there’s nothing to rest on, and your Air Drain would exponentially increase down here the further you go mostly because you’re not meant to get any further
This is a pretty neat concept, pretty neat indeed. Point Thalass scares the hell out of me though, because of how much you can accidentally mess up and fall into that incline, all for some untradeable hat.
Tempting, though I’d be too much of a p–sy for the first few tries.