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