The physics here feel quite well-implemented and the whole thing felt, well, immersive. I definitely felt the pressure on as your oxygen ticks down and goes from green to yellow to red. Plus picking up ocean plastic is a great theme. One thing is I wasn't sure how you know when the decompression stops were supposed to happen and I just ended up ignoring those messages.
Also, possible bug: I got to the surface and it said "You survived the dive" but then the oxygen kept counting down and it said "you died" a few seconds later.