This is a fun game and it looks quite polished, I love the art style here. Well done with the leaderboard and ghosts implementation, that was fun to see!
I was able to go down quite a bit though and with enough concentration it can be relatively easy to keep going down. It would be good if the further we went down the more damage hazards do when we touch them and maybe the less air we get from treasures, currently it feels a little easy to recover lost air by just hooking to a treasure.
I could see this being a fun mobile game :)
Overall real fun game, congrats on the submission!