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
There are approximately three million shipwrecks on the ocean floor, worth billions in value and treasure.
22
The Caspian Sea is also classed as the world's largest lake.
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Water is actually naturally blue.
48
There was once an undersea post office in the Bahamas.
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The North Atlantic gets 2.5 centimetres (1in) wider every year.
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The roar that we hear when we place a seashell next to our ear is not the ocean, but rather the sound of blood surging through the veins in the ear.
476
In 1992, 29,000 rubber ducks washed off a ship. They were found thousands of miles away 8 years later.
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