Really cool game !
Love what you did with the assets <3
Little feedback : The game over condition feels a bit sudden. Since there is a lot to keep track on screen, it's easy to forget to check the health and air level on the bottom of the screen. Adding a more visual indicator (screen going red or darker, or a HUD on top of the player sprite) for when the player is about to run out of oxygen or health would be a real + if you plan on updating the game after the Jam.
Great work !