This is Nick from Reddit. Very cool and atmospheric. I've experimented enough with physics to know how impressive this is. The controller and swimming is very smooth. I enjoyed the knife fishing. I loved the ending, actually frightened me!
Some recommendations:
With regards to the deep areas, they were well lit until I began to swim into them. I think changing this would add a lot of mystery to the experience.
I did fall through the map near the edges a few times. Also, the bubbles continue to appear when out of the water.
Overall, super impressive. I'm looking forward to seeing more of your work!