My colored version of the lineart I posted earlier - [link] Please feel free to tackle it yourselves, I basically went at recreating the famous poster - [link]
I didn't do it very well, but the technique is just... several layers with the round brush, in a slightly displaced fashion, and faded around the edges. If your computer's cool you can also try smudging to get that same effect, but mine freaked out at the smudge tool's processor usage. Otherwise I'd probably have blended in the waves a bit more. It really helps to look at references too, which I didn't. Here are some: [link][link]