Tell me what are you thinkings about it :p
compositionally, it looks okay to me. But it could use way more detailing, -I can't really make out any detail yet. Is that a sub? What is the sub lighting up?
Looks nice! The green of the rocks in the middle is nice, but I would expect in on the ones in front aswell. Now it's blue-green-blue from front to back.
You could try using a very big soft brush to make the water less clear. Works great for depth aswell if you do it on a layer and erase out what is closer to you. See this threat on for a clearer explanation I just posted about fog.
Hope this helps