Wayyy too difficult.
The animation wasn't half bad, but the game play was terrible. Sorry.
Some advice:
1) Don't make the swimming function like that. Make it so that you just hold in the right key or something.
2) Don't make it so that you have to sit there repeatedly pressing the space bar just to fill up your breath meter. That's extremely unrealistic. One breath should do the trick.
Better luck next time :)