Sơn Đoòng tops list of 10 greatest natural caves in the world
Originally discovered in 1991 by a Vietnamese man called Hồ Khanh, Sơn Đoòng Cave is located in the Phong Nha–Kẻ Bàng National Park, Quảng Bình, and was recognised as a world natural heritage by UNESCO.
Source: vietnamnews.vn