Attached Link: http://www.renderosity.com/viewed.ez?galleryid=306969&Start=1&Artist=Doublecrash&ByArtist=Yes

I agree with the comment above, mostly, but I think the images lacks somehow the murky feeling you have when you're underwater. To accomplish this (and avoiding the render-monster Volumetric World, although I still consider it the best way to achieve the result), you can maybe try to assing a volume material to your caustic-gel ligths and see what it comes out. If you want an example with VW (it's only an example, nothin' more than that), maybe you can see my gallery entry "Comparing 3 Different Bryce Renders" (the link is above) which explains the pains :-) I underwent in doing my first underwater image.

Hope it's useful,
Stefano