The music is superb and really gets your heart racing! Overall, great game/adherence to the theme.
If I can make any suggestions, I think there needs to be more HUD elements for telling us battery/oxygen levels. I couldn't tell if there's a difference in how long I stay at the air bubbles to catch my breath... also, the flashlight feels way under tuned with its battery life. I'd often run out of light before breath and just get lost and give up. I'd honestly prefer a full reset/loss of progress on death.