Most cruise lines put the guest’s cabin number right on their onboard account card (which doubles as a room key). Margaritaville at Sea prints the entire cabin number on the card, while Royal Caribbean puts the room number,

Few passengers know that this item, which many people pack, is no longer allowed onboard (it technically never was).

Carnival Cruise Lines took to social media to remind passengers about one of the basic rules when it comes to being on a cruise ship.