The World’s Largest Cave Was Discovered by Chance — Then Vanished for 17 Years

Deep inside Vietnam’s Phong Nha–Ke Bang National Park lies Hang Son Doong, the largest known natural cave by volume. Its passages are so vast that aircraft and skyscrapers are commonly used to explain their scale, yet the entrance remained hidden by dense jungle for millions of years.

The cave’s modern discovery began with local woodsman Ho Khanh, who encountered it accidentally in 1990. He left without exploring and could not retrace his route for years, turning one of Earth’s greatest natural wonders into a place that had effectively vanished again.