Hang Son Doong: Even a skyscraper could fit into the world’s largest cave

Less people have seen the inside of Hang Son Doong in Vietnam than have stood on the summit of Mount Everest

Less people have seen the inside of Hang Son Doong in Vietnam than have stood on the summit of Mount Everest

Hang SÆ¡n Đoòng in Phong Nha-Kẻ Bà ng National Park in Vietnam was discovered by a local man in 1991.  Located near the Laos-Vietnam border, it has the largest-known cave passage cross-section in the world by volume – 38.4×106 cubic meters (1.36×109 cu ft). It is more than 5 km (3.1 mi) long, 200 meters (660 ft) high and 150 meters (490 ft) wide and has its own river, jungle (as sunlight enters sections of it resulting in the growth of trees and other vegetation) and climate. It has only recently been explored (2009-2010) by the British Cave Research Association, and opened to the public in 2013. Formed in Carboniferous/Permian limestone, the cave contains some of the tallest known stalagmites in the world, which are up to 70 m high.

In 2013, the first tourist group explored the cave on a guided tour, and since then, permits are required to access the cave and are made available on a limited basis (800 permits available for the 2017 season, which runs from February to August). Plans are being considered to build a cable car through the cave, a system proposed to be 10.5 kilometers (6.5 mi) long and estimated to cost between $112 and $211 million.

"The entrance is quite small and mist from the cave, caused by the cooler air inside meeting the hot air outside, rises into the surrounding forest", says Australian photographer John Spies, who spent a week photographing the natural wonder of the cave system. He adds that "visitors must descend 80m down a steep wall with the use of harnesses and ropes. The huge temperature difference also creates moving clouds of mist, especially near the two karst windows, which gives the cave its magically surreal atmosphere. It is amazing to be 3-4km inside the cave and have daylight illuminate the cave formations. The dimensions of the cave are incredible and to camp for five nights in the biggest cave in the world is not something most of us get to do in our lifetime".