Sơn Đoòng: The Lost World Under Vietnam
Concealed deep within the jungles of Phong Nha–Kẻ Bàng National Park, along Vietnam’s border with Laos, is one of the Earth’s most marvelous natural marvels — Sơn Đoòng Cave, the biggest known cave in the world. It is named “Cave of the Mountain Behind Đoòng,” after a local Vân Kiều village. Created 2 to 5…