I have been on several nude cruises and highly recommend it.
The trips I took we're not Swingers cruises but rather, Clothing Optional, though there was likely swinging going on amongst those who so chose, privately negotiated.
My experience is that these trips are more costly than Textile cruises, but you can't beat being able to spend sea days totally nude all day long (except for the dining room, which requires some form of dress).
Another advantage is that the cruise organizers work with the excursion providers to allow some excursions to be enjoyed nude. Those are usually snorkeling or catamaran or sailing excursions because that's easier to accommodate without offending the locals ashore. They do not advocate exhibitionism but make opportunities available wherever possible, for passengers to get the most out of being nude on vacation.
Clothing is also typically required when the ship is in port.
Regardless, it's a fantastic way to relax and get the most out of your vacation if you value being naked and enjoy social nudism.