Cruises are mostly pretty fun. You get to travel around for a while, visit foreign countries, and hang around old people who couldn't think of another kind of vacation. But sometimes cruises can be a little on the scary side. After all, if you go to shore but don't make it back by the time the ship leaves, you're in a lot of trouble. Not to mention, if you fall over the railing... that's about it for you. Cruise ship disappearances are a real thing, and they happen more often than you'd think.Most of the time, people fall off the ship and disappear at sea. Sometimes, they simply vanish from the ship itself, never to be heard from again. It could be kidnapping or murder, but these cases almost invariably stump the FBI. So, next time you think about going on a cruise, check this list and make sure it's really what you want.