I love the concept.
The underwater theme is excellent. Your intro is highly creative and transitions well into the rest of the song. I almost wish the entire track followed suit; up until 1:25 you had me zoned out, which I love to do when I listen to ambient music. But the increased volume due to the addition of parts kinda snapped me out of it, haha. The various parts are balanced well dynamically, too, which helps the whole ambient factor of the song out a good deal.
I'm an ambient artist myself, (along with techno and electronic in general) so I'll probably listen to this song for a bit when I need to get in the mood.
Real good stuff, I'll check out your other songs and see how they are too. Definitely get this into FFR if you can; this is the kind of music the game needs to save itself.
This is GamerShadow, in case you were wondering. =)