The longest cave in the world is the 'Mammoth Cave System' in the USA at 560,000 mtrs deep!
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Mexico City is built on top of an underground resevoir!
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The state with the longest coastline in the Continental U.S. is Michigan.
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Israel's Dead Sea is 1,312 feet below sea level.
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The water between India and Sri Lanka is only 3-30 feet deep and was purportedly passable on foot until 1480 AD when a cyclone moved some sand around.
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The North Atlantic gets 2.5 centimetres (1in) wider every year.
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An earthquake on Dec. 16, 1811 caused parts of the Mississippi River to flow backwards.
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