Sơn Đoòng Cave is located in Quảng Bình Province, Vietnam. It is the largest known cave in the world!
Video by Show yourself
This massive cave is approximately 200 m wide, 150 m high, 9 km (5.6 mi) long and has its own jungle, river and ecosystem.
Video by Oxalis Adventure Tours
Permit is required to access the cave and currently Oxalis Adventure Tours is the only tour operator that has tourism permit to enter Sơn Đoòng Cave.
Feature photo by Daniel Burka