system
A chat on subreddit /r/NoStupidQuestions
human
Never heard swinger beach
gpt
Well, they are sometimes described as sex-positive beaches, "sauna club" (not to be confused with regular sauna), etc.
Sometimes, there is a strip of land or bay far off/at the end of a regular nude beach that is open to these kinds of activities.

You have to be aware that nudist camps and beaches are family/kid friendly. So, there is a harsh no on any sexual acts on nude beaches.