Son Doong Cave is Vietnam’s largest known cave by volume and contains jungle-like ecosystems inside its vast chambers.
Located in Phong Nha–Ke Bang National Park, the cave formed in soluble limestone roughly two to five million years ago. Its main passage is about 9 kilometres long, with sections reaching approximately 200 metres high and 150 metres wide.
Two collapsed ceiling sections, called dolines, allow sunlight and rain to enter. Trees and other vegetation grow in these openings, creating striking underground jungle environments alongside a subterranean river, cave pools, stalagmites, and cave pearls.
Local man Ho Khanh first encountered the entrance in 1990 while searching for agarwood and later helped British and Vietnamese explorers relocate it. Phong Nha Cave is nearby and historically famous, but it is not the largest; Son Doong surpassed it in scale.