I don't mind the controls, I think it's fine.  I'm not sure how building up speed seems to factor into the gameplay though, it seems like it matters for a little bit at the very beginning of the game.  I also think that surviving in the game becomes trivial after a little bit.  I think you could have improved the game by removing death entirely, putting the game on a 30 second (or maybe one minute to fit the theme) time limit, and then having bombs only stun you.  That way speed matters more and the game has a more interesting way to challenge yourself.  Note also that there's a bug where if you reset the game, your score doesn't reset.

As olinkalex said, the 'one button controls' make the game a little clumsy and frustrating sadly...

I feel like the Only One Button control doesn't works for this type of game. Its confusing and annoying to try and control the shark with one button and having to keep pressing it or you die. if you just have to press to swim and not die and you control the direction with the mouse then that would be fine. or Just control the shark with one button but not needed to keep pressing to survive.