In fooling around in the DTE I found a fairly nice way of simulating UW caustics using procedural textures: Here I used Voronai DistSq1 noise set to 3D and scaled to about 30 in all directions. Make the top color bead black, middle grey, bottom white and stick the texture on a light. you can animate the frequency in one of the directions or experiment with animating phase. just a quick render, I think with some fiddling the effect could be more convincing

Uh, tutorial with pics? I think I follow but I'm not sure...

Cool! Nice to see a "native Bryce" solution to a question I had not long ago! The effect looks great in this pic!

Also, you could take 2-4 spotlights, give them these as gel maps, place them over the image and put each on a circular track, then you just loop the spotlights (pointing down) each moving randomly around a different track, creates extremely realistic movement, especially if you mess with their accelerations in the AML.

excellent!!! No more searching the web for caustic gels.

Looks very realistic and sounds so simple, but I'm with Zhann, ie. unsure. Catlin

Here's a screen capture. first create a light, in its edit window put a dot by Use Gel, click procedural, in the mat lab put a bead in the diffuse column then in the dte use the above settings. hope that helps. you could also try the texture as 2D instead of 3D I think you get fewer "clumps"