Beautiful location! I like what's going on in the right half of the photo so I probably would try an 8x10 crop of that area (I know it's a pretty aggressive crop for a D700 but still good for websized photos) and exclude both the cabana (looks like a lifeguard station to me) and tree trunk.
To me, the silhouetted kids in the water should be the main subject and you don't need the other two elements in the frame. If there was a silhouetted lifeguard in the cabana, that would add to the story and then I'd say keep it.. but since it's empty, I would try cropping. Much less Photoshopping required!