The Hang Son Doong in Vietnam is the world’s largest cave system. The name translates to “mountain river cave” since this cave in the Annamite Mountains contains a river and jungle in it. It is in places three times the height of Niagra falls and big enough to accommodate a New York City block of skyscrapers.
The biggest chamber of Son Doong is over 6 km in length, 200m high and 150m wide.
The cave system was first discovered in 1991 but no one entered the cave until 2009. What the expedition found inside the cave system is simply breathtaking!! Nothing short of another wonder of the world! Some pictures from National Geographic’s 2011 issue:
http://ngm.nationalgeographic.com/2011/01/largest-cave/peter-photographyWhat struck me the most were the beautiful, bright green plants growing inside the cave. BBC is working on producing a documentary on the cave including details of the rare vegetation and animals found in the area.