They're built to be unsinkable.
But even the most robust ships in the world have been known to lose their battle against the mighty ocean when conditions get bad enough.
Fishing boats regularly face the wrath of the sea, as photos here display. One shows a Scottish vessel in the North Sea caught in mountainous 30ft waves, and another reveals a fishing boat in the Irish Sea that had to summon the Royal Navy after getting into trouble amid a storm.
Cruise ships occasionally find themselves in tumultuous situations too.
In 2010, an Antarctic cruise liner with 88 passengers and 77 crew members aboard sustained serious damage after being battered by brutal waves and 55 mph winds when it was north east of the South Shetland Islands on its way to Argentina.
These stomach-churning shots, rounded up from around the world and stretching from the 1920s onwards, capture the sheer power of the waters that cover more than 70 per cent of our planet.