I really enjoyed your game. The music is cool, the graphics are simple and pretty. Too bad the bubbles behind the submarine "teleport" when you change direction. I didn't use the shield much, I think I would have preferred a dash. I did 750 with DivingSpeed level 2. So I think level 3 is a bit too high and makes the game too easy once unlocked.
Great treasure for the cat in the end chest =)