A waterfall known as The Devil's Kettle empties water into a hole and nobody knows where it ends up!
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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 city of Houston, Texas is built on a swamp and is slowly sinking!
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The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
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Venice Island was built on a foundation of tree trunks. 1200 years later, those same trunks still support almost all of central Venice.
8
Forest fires move faster uphill than downhill.
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The Caspian Sea is also classed as the world's largest lake.
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