On my screen the ocean is almost purple!
Assuming you were intentionally going for a silhouette, I think the contrast is fine. The important thing for silhouette's is that the subject be recognizable in profile, so this works for me. You did a nice job of aligning things so that he is nicely framed by the white sand.
Black is a bold element and to my taste it needs to be given its just allotment of space. I think I would have liked this better if you had moved back to include more of the tree trunk on the right. A slightly lower angle would have given space between the horizon and leaves, and l think that would have been a good thing. If there was a branch above the top of the frame I might have included some of that too in order to have the black wrap more around the frame. All judgement calls -- food for thought.
Regards!
- KenF