groovybaby,
There was a naturist resort that opened in the Datca area, Hotel Adaburnu Golmar. However, it was forced to close 6 days after it opened by authorities due to a problem with the balconies. I don't know if it ever reopened or not. It was the first, and only naturist resort that I know of in Turkey. Naturism isn't a big thing in muslim countries and frowned upon so I'm not aware of any naturism beaches. You'll have to put up with tan lines!
Darren