I think I would have left out the bottom half completely. There is so much going on in the top with all of the rocks and I think the plain sand in the front really takes away from it.
This is a great composition. I had to come back to it and am bumping it from a 5 to a 7. I like the leading affect it has on the viewer with its nice curves in the foreground. The little tunnels in the back actually take away something from the photo, IMO, but if you cropped them out, then you lose most of that nice rock on the right. 7.