The Smithsonian Magazine recently listed Kentucky’s Mammoth Cave National Park as one of the top ten geologic sites in the country. Mammoth is the longest cave in the world. Only 360 miles of the hole has been surveyed so far, but geologists estimate that the cave system’s total length is about 1,000 miles. No other cave even comes close to that size. 

The cave was listed as number 8 on the impressive list, which also includes Mount St. Helens, Niagara Falls, and the Grand Canyon. 

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