Not too bad.

~ Animation/Graphics ~

This was really the biggest downfall of the whole submission. I can see the basic simple drawings working. They could have been more detailed, but I think they were fine enough for what you were doing. The thing that I think would really help would be doing what I like to call in between animations. Such as the divers legs/arms moving in a swimming motion instead of the diver just being tweened across the stage.

You could go even farther and make it so the fish/sharks fins swam or had some bubbles coming up like they were breathing.

~ Story/Content ~

I can't comment too much here as it was for a school project and it looked like it was mainly for practice, etc.. Perhaps you could have had the diver go and find some treasure and then get attacked. I don't know exactly what you were suppose to do or anything though.

~ Audio ~

Not bad music all around. There wasn't much room for sound effects or anything of that nature so the audio was about as good as you could make it.

~ Overall ~

Work on your in between animations and I hope you did well/will do well on your school project!