His head blends into the dock too much. I'd either dodge the color to make his head stand out or get on another angle. He's also too close to the center. Crop it closer towards his back. I love the feel of this picture though. It's more natural. How many of us know that feeling of our feet sinking into the sand after a few waves come in.
Shallower DOF might have worked (and closer to the subject?), since the pier and buildings in the background are distracting. But overall an imaginative shot, well composed.
Your focus is a little soft. I don't mind that so much, however you are also blwon out in the highlights and the guys head dissappears into the pier... Taking a shot that isn't exposed properly and turning it b/w will usually only accentuate the fact that it's not exposed properly...
TC