More than a dozen men have stood on the surface of the moon, but only three have been to Challenger Deep in the Marianas Trench, the deepest known spot in the ocean.
17
The Caspian Sea is also classed as the world's largest lake.
52
The North Atlantic gets 2.5 centimetres (1in) wider every year.
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There are approximately three million shipwrecks on the ocean floor, worth billions in value and treasure.
22
Scientists have confirmed that Enceladus, one of Saturn’s moons, has a watery ocean.
6
There was once an undersea post office in the Bahamas.
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In 1992, 29,000 rubber ducks washed off a ship. They were found thousands of miles away 8 years later.
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