Wow. That's gonna be a long one to write out... I think the important factors are these: 1) Ambient light should be blue-green, and very dim. 2) get an image map of some water waves (Like when you are looking at a pool, not the kind you surf on) and use it in a large projecting spotlight on your scene. I've found that this, combined with a soft, gently rolling landscape (terrain) makes a pretty convinving underwater scene. These are just the basics, obviously. Good luck! Hoborg