There is plenty to discover in Hang Son Doong cave in Phong Nha-Ke Bang National Park, Vietnam. The cave is one of the largest in the world and requires a licensed guide to explore.
Photograph by Cartsen Peter, National Geographic Creative
Located within Phong Nha-Ke Bang National Park, Hang Son Doong is one of the world’s largest, with its main cavern big enough to house a Boeing 747 plane. A wide, fast river that tunneled through the Earth over time formed Hang Son Doong, whose name translates from Vietnamese to “mountain river cave.” Ho Khanh, who took refuge within it during a storm, discovered Son Doong in 1991. Lost again until 2009, the cave is now open to tourism. Proposed developments, including a cable car, have raised concerns with environmentalists. For now, only Oxalis Tours is licensed to guide tourists through Hang Son Doong.
Getting There: Oxalis offers multiday expeditions for $3,000 (U.S.). An alternative for those in the area is Thien Duong Cave (Paradise Cave) in the same national park. Buses run to Phong Na from Dong Hoi and from Hanoi.