Hmmm she's second from right in the above picture of us on pool noodles with Efes, but I'm not sure one can determine her bikini color in that picture, certainly can't appraise her booty there. Though note the water is so clear that you can actually see several of our feet!

Perhaps you are referring to this picture, under the link about nosing the boat into the cave:



Which isn't a terribly great picture of Michelle but that's one of the two Spanish girls on the right in a bikini that looks plausibly turquoise?