The concept and controls are really nice, it also depicts quite well the darkness and claustrophobic feeling of underwater caves. I really enjoyed it. I also love the menu visual where you can see the oxygen and battery, that looks awesome.
The only thing I didn't like is the crackling of the sound. I don't think that was intentional, but if it was, personally I find it quite unpleasant, Also I am unsure how is the limitation of Time is a resourse done here as it feels like the oxygen and battery are more of a resourse than the time itself, but you are technically still "racing" against the time so not sure.
Otherwise good job.