The Rao Thuong River flows fast through the Son Doong cave system, continuously carving

Hang Son Doong, the world’s largest cave. Located in Phong Nha-Ke Bang National Park near the border of Vietnam and Laos, Hang Son Doong is one of the most incredible natural wonders of the world — and the tale of its discovery is just as fascinating

Hang Son Doong was discovered in 1990 by Ho Khanh, a local Vietnamese man who was out hunting in the park. While seeking refuge from an approaching storm he found a large opening in the side of a cliff, with clouds billowing out. He neared the entrance and could hear a river deep inside. The steep and dangerous rocks meant that Ho Khanh was unable to explore further, and he left once the storm passed.

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