Wonderful concept. It must have been a great find to find a rock formation like that. The hole being located slightly to the left-center gives it a fleeting sense. Her contained form slightly obscured by the curved rock does well, too. I'd like to see the expression on her face more somber, or hidden. The corner in the upper-left appears to take away from the composition, though.
Overall, wonderful concept. Could use to fix a few things.