Sơn Đoòng cave in Phong Nha-Kẻ Bàng National Park, Vietnam

Sơn Đoòng cave in Phong Nha-Kẻ Bàng National Park, Vietnam

© David A Knight/Shutterstock - 2021-01-02

Rock Atmospheric phenomenon Formation Geology Cave Bedrock Natural arch Erosion Outcrop Green algae Fog Moss