I have a friend who went, yep, there's sections to these places. Some nude, some prude and there are areas where you do have to wear clothing.
That being said, many swingers go here as well. People like to explore in places where people won't know who you are so there's no pressure that "someone will find out".
So be prepared to also be offered to couple with others, one on one, groups, etc. Not sure if they allow "anything" to happen in the open, but hey, you never know.
And Yes...before people go ewwww....you do have to have a medical exam in order to stay at these places and must be submitted to the resort which they do in turn, verify. Anyone with AIDS, STD's, etc apparently are not allowed to stay.