I like the lighting and the concept, but the two main things I would change are making sure the feet can be seen and then cropping a little above everyone's knees rather than through them. If waiting for the water to recede in order to see the feet, I think the shadows on the sand might look good enough to give more frame to the shadows than the legs, but with how choppy the water is distorting the shadows I think it would be better to give more frame to the legs than the present 50/50 split. I don't want to sound like mine would be better or anything, these are just my thoughts on how I would want change it next time if it was my own photo.