I'm using lots of lights (dozens) with deferred rendering path, but lighting a water surface with all of them isn't that important. I could use only a couple of them to light up a water surface. What I want to achieve is a flooded room/building that a player can explore by walking across it and from time to time he would be able to swim or dive. Water would have to be attached to a plane or a box (volume). Believable surface of a pool and underwater fog are crucial here. Ps.Unfortunately I can't show you this interior. I could do a 3d prototype, but I think that my description cleared up what I meant .