Interesting photo shoot on this one. Too bad about the few imperfections from the background and foreground. They'd be out in post processing of course if this wasn't a basic challenge.
I like the idea. Its just hard to execute. It would be nice to clean up the shot with some cloning (e.g. the bright spot in the top left, the stains on the pool bottom and the spot in the upper left). I like the colors and the poses are good. Its interesting that the one guy is wearing just one flipper while the other guy holds the second one.
Very fun idea and composition. I wish the guy standing up was lower in the picture so you could have cropped the top portion of the image out. I find the light blob distracting.
From a composition standpoint, this is a great setup - at first run through, I missed the point about no water and the model's expressions - that's pretty clever. Unfortunately, the upper left light blooms and the general washed out colors from a soft focus don't do the image any favors. The models are an intersting mix of hair style - a good effort.