Loving the idea of doing a silhouette! The upper part with the shark and surface is nicely pixelled, the rest not that much unfortunately. Perspective and rocks look quite odd.

Awesomeeeeee!

I was going to do something like this too for my hammerhead, the shark and water are very good and the rocks suit the piece too, I'm not sure about the bands of blue for the rocks going into the distance. Do they need to be lower as we're looking up at the shark from underneath?