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World's Biggest Cave Facts

The entrance to a doline. Dolines are mini-jungles that were created when the cave ceiling collapsed inwards allowing daylight to stream in and the creation of unique eco-systems.

The entrance to a doline. Dolines are mini-jungles that were created when the cave ceiling collapsed inwards allowing daylight to stream in and the creation of unique eco-systems. (View larger version)

Photograph by ITV STUDIOS LTD./ Simon Reay

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  • There are incredible caves throughout Vietnam in areas like Lang Son, Cao Bang, Son La, and Ha Giang.

  • Central Vietnam’s Karst region is about 300 miles from Hanoi. It contains magnificent limestone caves.

  • Phong Nha-Ke Bang National Park is near Vietnam’s border with Laos and contains incredible limestone caves.

  • The vast network of chambers that make up Hang Son Doong, or Mountain River Cave, are in northwestern Vietnam.

  • When he was young, a man named Ho Khanh found the Hang Son Doong, or Mountain River Cave, network.

  • Hang Son Doong, or Mountain River Cave, was formed between two and five million years ago. River water moving across limestone flowed down along a fault, forming a giant tunnel beneath the mountains.

  • Although there are longer and deeper caves than Hang Son Doong, or Mountain River Cave, few other caves can compare to its giant passages.

  • Hang Son Doong, or Mountain River Cave, contains trees that are one hundred feet tall.

  • The cave pearls in Hang Son Doong, or Mountain River Cave, are huge: about the size of baseballs.

  • Cave pearls form when a drop of water from the ceiling hits the limestone floor, throwing up a speck of rock. The grain of rock moves in its cup of stone every time a drop of water hits it. It takes thousands of years from the calcite pearl to form.

  • The cave pearls in most caves tend to be about the size of a marble.

  • It’s estimated that an entire New York City block would fit inside Hang Son Doong, or Mountain River Cave.

  • The mud walls inside Hang Son Doong, or Mountain River Cave, are sticky and have been compared to the texture of peanut butter.

  • Phong Nha-Ke Bang National Park attracts about a quarter million Vietnamese tourists every year.

  • Around 90 miles of cave passages have been discovered in the rain forest along the Vietnam-Laos border.

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