Son Doong is the largest cave in the world. It is located in central Vietnam's Quang Binh province. Son Doong, which is estimated to be 400 to 450 million years old is now part of the Phong Nha-Ke Bang National Park, a UNESCO heritage site.
The cave has a total length of 9 kilometres and has the largest cross-section of any cave anywhere on the planet. It comprises around 150 individual caves, a dense subterranean jungle and several underground rivers.