While not an "official" activity sponsored by any mainstream cruise line, the "swinging" (lifestyle) community does have a significant presence in the cruise industry through full-ship charters and private groups. Companies like Bliss Cruises and Temptation Cruises specialize in chartering entire vessels from major lines (like NCL or Celebrity) specifically for lifestyle-focused vacations. On these chartered sailings, the entire ship becomes an "adults-only" environment with themed parties, clothing-optional decks, and "playrooms," allowing members of the community to socialize openly. On a standard, non-chartered public cruise, swinging is much more discreet. There is a long-standing "urban legend" that placing an upside-down pineapple on a cabin door is a signal for swingers, though in reality, most participants use private forums or organized meetups to connect. Most mainstream lines maintain strict codes of conduct regarding public behavior, so any lifestyle activities on a regular sailing are kept strictly behind closed doors or within private, pre-arranged groups. If you are looking for this specific experience, it is highly recommended to book a dedicated charter rather than a standard family cruise.