Berrecco has a pattern that I highly suggest you do NOT try! I spent all this time on it last year, and I swear, I'm not sure what kind of woman would fit in that thing, very strange.
I'm trying to find yarn for one as well. I'm thinking I'm going to go with the one in Hollywood Knits by Suss Cousins. It's a pretty simply bikini pattern, and it says it's not for swimming, so I'm trying to find a yarn to make it more adaptable.