That's a really nice POV. Daring (for the guy as well), but worked out really well. I like the sense of depth you get from this scene. The transparency of the water is just right, but there's a thing that I noticed; on the right side there's quite a distinct line between deep water and less deep, as if the fuzzy zone of transparency (which there isn't) wasn't soft enough. Any idea how come?
And in the center of the lake there's a reflection that bothers me, it's very straight. Coincidence from a steep rise in the mountain overhead, but nevertheless a bit distracting.