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.
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Australia's Great Barrier Reef is 1,250 miles long!
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An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
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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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Due to gravitational effects, you weigh slightly less when the moon is directly overhead.
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Mexico City is built on top of an underground resevoir!
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