Son Doong Cave System

Sơn Đoòng cave, in Phong Nha-Kẻ Bàng National Park, Bố Trạch District, Quảng Bình Province, Vietnam, is the world's largest natural cave. Located near the Laos–Vietnam border, Hang Sơn Đoòng has an internal, fast-flowing subterranean river and the largest cross-section of any cave, worldwide, believed to be twice that of the next-largest passage. It is …
Sơn Đoòng cave, in Phong Nha-Kẻ Bàng National Park, Bố Trạch District, Quảng Bình Province, Vietnam, is the world's largest natural cave. Located near the Laos–Vietnam border, Hang Sơn Đoòng has an internal, fast-flowing subterranean river and the largest cross-section of any cave, worldwide, believed to be twice that of the next-largest passage. It is the largest known cave passage in the world by volume.
  • Location: Quảng Bình Province, Vietnam
  • Length: approx. 9 kilometres (5.6 mi)
  • Depth: max. 150 metres (490 ft)
  • Discovery: 1991 [AD] by Hồ Khanh
  • Geology: Permo-Carboniferous limestone
  • Entrances: 2
  • Hazards: Underground river
Data from: en.wikipedia.org