At some point we have all wanted just such a button, but just like the fabled "Make my Render Beautiful" button, it's just not possible. There are way too many variables. But just because there isn't a pre-built button/option, doesn't mean you can't create some beautiful under-water scenes. Like most things in life, it just takes a little work.

First let's discuss water itself. You would thinque it would be as easy as just building the scene itself, water is after all clear. Yeah, you guessed it, its not that easy at all. The thing about water is that it is usually not clear at all. It often appears to have a slight color, and depending on the water in question, can appear murky due to sediment, plankton, algae and other microscopic debris. There may alos be bubbles present depend-ing on what else is floating about in the water. Luckily, most of this can
be easily created in the material set-tings themselves. And any number of interesting bubble effects can be cre-ated with a creative combination of particles and software bodies.

Note:A number of great material shaders can be found at:
1) Blender Open Material Repository
2) Blender 3d: Noob to Pro

So now we have realistic wa-ter, rightí

Nope, not yet.

Now we have to tackle the whole lighting issue. Water has this annoy-ing habit of reflecting, bouncing and diffusing light, producing of course, caustics and volumetric light. In a nutshell, volumetric light is pro-duced by the light rays bouncing off all the microscopic debris floating in the water. The patterns of light (caustics) are created when that bounced, diffused light falls on ob-jects in the water, such as rocks, fish or the sea floor, riverbed etc.

Now of course, we could export our scene to an external render engine, that handles volumetric light and caustics. The results would be as you expect and as a bonus, you would have plenty of time to go find some-thing else to do while you waited for
it to render. :P

But where is the fun is in thatí

Instead, we are going to fake it.
There is always a way to fake an ef-fect. First we have to decide just what we are trying to fake. So what are we going for? Well, we need software, fuzzy light beams and some pretty light patterns. It can't be that hard.

Now I know that fuzzy software lights can be created with spotlights and halo options. But here I always run into problems. I don't know about you, but whenever I attempt to use halos, I end up with a huge fuzzy cone of light that completely blows out my image. Not a good underwa-ter look, and we haven't even ad-dressed the caustic part of the problem. This just might be harder than I thought.

I may not have a lot of luk with ha-los, but I am Queen of Google searches. There is a wealth of Blender information online, but oddly enough it tooque quite a while to find just what I needed. Eventually I found my solution in the form of an excellent, in depth tutorial at, the tutorial not only covered underwater volumetric lighting but the underwater caustics as well.

Well there you go, step by step in-structions on how to achieve that magical underwater lighting. Using a rather ingenious combination of special rotating discs and procedur-als, the tutorial covers how to go about setting everything up, and as a bonus even covers the trickier sub-ject of animating those light beams and patterns dancing on the sea floor.