Anyone know how do make a scene looking like its underwater?

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

The Carrara 1 Bible has a tutorial for an underwater scene right off the bat, using distance fog etc.

Be sure to use some pretty heavy distance fog -- it really murks up an image. Also, use spotlights and light cones with shadows turned on. In post production, you can add a billion little bubbles floating around, too....