Explore the ancient caves of Hang Son Doong, Vietnam. Hang Son Doong is one of the largest caves in the world and features a fast-flowing underground river. For spelunkers, exploring Hang Son Doong is the equivalent of scaling Mount Everest.
Blyde River Canyon is Mpumalanga, South Africa. It is a 26 km long, 2500 deep canyon covered with vegetation, making it the largest green canyon in the world. Read more: AfricVilla: Today's photo: Blyde River Canyon, South Africa