rundown of everything you can find (spoilers)

[epic meow]

some kind of seaweed or underwater flora that can presumably grow and survive in blood.

skeletons shards

skull and ribs

ribs with no head / skull

fish monster duh. fish monster's eye (presumbaly) and then the fish monster again. at the last sighting there's an invisible wall or force preventing you from speeding past it, holding you back. probably not significant to the story or world but merely a gameplay thing so players don't sequence break.

tubes that sound like they're extracting something from the earth? some kind of sloshing noice, liquid noise although it could be a scraping noise. don't think it's a worm as it doesn't move. looks and sounds like tubes. not unthinkable seeing as how there are other constructions in the sea of blood which are presumably man made.

buildings, pillars, bricks, corridors, possible crashed ship. very randomly distributed, no buried city layout of district. just a single building in the middle of nowhere and other structures that are completely disconnected from the others. don't think a city was once here, if you believe in the teleportation hypothesis then we'd have to believe it teleported things in random chunks. all the structures are clearly from the same civilization as they share similar architecture except maybe for the tubes. it's unlikely someone built a building and a corridor 50 miles apart for no reason. could also be that the rest of the city actually is there but it's settled underneath the dirt and soil. i don't think so though.

subtle human faces that appear and reappear. human figures that are very small and look dead yet somehow move (but not in a very obvious way). maybe just a torrent or current moving them around? problem being that they don't "move" they just appear/disappear. these appear to have tissue, though likely decomposed, they're not just bones like the other creatures. is this significant? probably not. could also say they're lost souls or something. one appears to be a child (near the building). lastly this could be a red herring or some kind of rorschach effect but i don't think so.

unseen teleport wormhole thingy that can/does shake your sub and move it to different coordinates as you're sailing away from the building. some think this is related to the ball of light but this is very far from the building. don't think it's related to that. unless the teleport happens in different places / times for different players. tied to some flag that we haven't found or simply a random seed.

speaking of which there's said light ball that shoots beams and either distorts matter around it like some weird gravitational thing, or distorts the players vision. the light ball doesn't have collision and doesn't harm/kill you.

have i missed something?

EDIT: apparently there's a monolith / obelisk that makes a humming noise and another bone creatures that is only visible in the game files.

[epic meow]

i gotta say it's extremely intriguing

[a bitch of culture]

i definitely took a picture of some kind of face at one of the points of interest, but when i tried to take it again it was gone. i really wish i had taken a screencap.