I have always been fascinated with 3D water effects since the film Finding Nemo (one of my all time favourite movies).
My first large scale animation project, the Prehistoric Insanity logo, saw me try to tackle water head on.
Considering this was my first try at water, I'm surprised knowing what I do now how successful I was. It is really rubbish, but for a first try I nailed a few things. The problem is that in my inexperience (and older software) I was using the wrong tools and techniques to try and achieve the goal of underwater.
The light shafts you see in this animation are all individual lights, and there is about 40 of them if I recall correctly. That is way too many! In comparison these days on even my most complicated scenes (Karoo Sunset being the one that jumps to mind) I might use 5. Every light adds time to the render, and as I recall this 40ish second animation took nearly 48 hours to render.
The murkiness of the water is about the most cutting edge thing I managed in this animation. Though the tool has changed a bit between Raydream and Carrara, I still essentially use the exact same thing (just now I have more control and options... but ancient me can't be blamed for that).
Despite the fact it does my head in everytime I watch Finding Nemo, I always pick up one new thing to try. Pixar's "making of" special features have produced some real gems of insight (at other times causes me to despair as I don't have the software, tools, or manpower they do!)
The biggest one is light gels. I've played with these before, but up until yesterday I'd never had a high enough resolution animation of water rippling to pull off the underwater light shafts with but a SINGLE light. However I acquired a little brilliant program off the web yesterday that generates such ripples. So now I'm back on track with Kung Fu water (which I've been doing in still photos for a few years... but I could move or animate it to save my life!)