![[Teacher's Day: Solitary Search, Bravely Go Forward] Han Song-dong, Phong Nga Bang National Park, Vietnam](https://images.sonurai.com/HangSonDoong.jpg)
[Teacher's Day: Solitary Search, Bravely Go Forward] Han Song-dong, Phong Nga Bang National Park, Vietnam
© Carsten Peter/Getty Images - 2015-09-09
formation cave caving geology speleothem rock coastal and oceanic landforms pit cave
[Teacher's Day: Solitary Search, Bravely Go Forward] Han Song-dong, Phong Nga Bang National Park, Vietnam - Bing Wallpapers - Sonu Rai