I know bridge tournaments are a big thing on cruise ships. I think I've seen adverts for a chess tournament on a cruise ship several years ago but can't remember the details or find anything online. Chess tournaments on cruise ships don't seem to be a thing, maybe because of problems registering them for FIDE rating.
Suppose you were a cruise ship company wanting to stage FIDE rated tournaments. Given that they would take place in international waters outside the jurisdiction of any national federation how would you register your tournament for FIDE rating?
Normally if you want to register a tournament for FIDE rating you give the details to the hosting federation's IRO (international rating officer) usually via an automated online form and they register with FIDE.
I know there is a special federation, FID, for players who can't be registered with their national federation. Currently a lot of Russian players are registered as FID. In the past Iranian players who have been persecuted by their federation have moved to FID. But I don't think FID has an IRO through which you can register tournaments for rating.