Cruise ships are some of the biggest and safest vessels that sail oceans, rivers, and lakes around the world. But they're not immune to tragedy. Fortunately, modern safety protocols ensure that even when a ship sinks, it will almost always keep passengers and crew members safe. Still, some people are wary about cruising, especially when they hear that cruise ships have sunk in the past. But how many cruise ships have sunk, and what caused these disasters?

While it's true that a few cruise ships have sunk over the years, the instances are very rare. In fact, over the last 100 years, only 22 cruise ships have sunk while at sea.

Some of these incidents are the result of bad luck, but others are due to human error. In 1994, the MS Estonia sank after hitting a storm, killing 852 of its passengers and crew members. It's believed that the ship was in disrepair at the time of its sinking, with loose hull plates and stripped check valves, as well as a hole in a bulkhead between the sewage tank and generator room.

Other disasters are due to poor decision-making by the captain or crew. In 2012, the Costa Concordia was sailing to Isola del Giglio, Tuscany when it sailed closer to the island than it should have. This led to the ship hitting an underwater ledge, which then caused it to list and eventually capsize. The captain of the Costa Concordia was later convicted of manslaughter, although some say that his actions were justified.