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Explore the World's Largest Underwater Cave

The world's longest underwater is located near the city of Tulum, on Mexico's Yucatán Peninsula. The discovery connected two previously known flooded caves into one 215-mile-long stretch. The cave holds an important large fresh water reserve that supports great biodiversity. Hundreds of archaeological sites exist in the cave, including evidence of America's first settlers, Mayan culture, and extinct animals.

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