This was not as expected from the description and track titles. There are some pleasant watery sounds, and I think overall I would have been satisfied were it not for the degree of looping and the constant crackling & static noises. I get the impression that it's the result of some technically clever underwater microphone techniques, but with the noise (one imagines perhaps grains of sand constantly hitting the mic) it does not make the serene, ambient experience I was hoping for.
I love listening to water sounds - for sleep and relaxation - though I found that I just can't sleep to the sound of *crashing* waves. I'm also not that into music overlays if they are not done right they can have the opposite effect for me. I prefer white-noise to sleep - something constant and non-surprising.
However this one's very pleasant. The hydrophone stereo 3D recording is quite brilliant, it's difficult to explain but listening to them with noise-cancelling ear phones (especially track 7) I have physical reaction to the sounds.
The track(s) with music overlays were spot-on; constant and no 'gaps', flows very nicely.