Shipwrecks occur every year. It is thought that there are at least 3 million vessels lying wrecked on the sea bed somewhere in the world.

Shipwrecks are mostly the result of accidents. For example, a ship might lose engine power in a storm, and be driven by waves and wind onto rocks. A ship may be overwhelmed by huge ocean waves. It could begin to leak when a plank or sheet of steel buckles or breaks. The ship may strike an iceberg, as famously happened with the Titanic (for more see: Titanic entry).

Some shipwrecks are the result of battles. Many ships lie on the seabed as a result of battles in the first and second world wars.

Some people seek out shipwrecks because they know they were ancient treasure ships, especially those that sank on the journey from the Spanish Main to Europe in the 16th and 17th centuries. Others seek them out to recover some of the goods and even the whole ship for historical reasons. The most famous example of this is the Tudor warship Mary Rose.