Hang Son Doong is the largest cave in the world, situated in the central part of Vietnam near the border with Laos. It has about 9 miles long - the largest of its chambers has more than five kilometers - 150 meters wide and 200 meters high.
The cave’s enormous dimensions has allowed stalagmites to grow up to 70 meters tall, the tallest known stalagmites in the world. Despite its enormity the cave was only discovered in 1991 by a local man, but the local jungle men were afraid to explore because of the whistling sound the underground river made. It was not until 2009, when a group of British scientists from the British Cave Research Association conducted a survey, that the existence of the cave was made known to the public. Later, a team of explorers from National Geographic came up with some of the most stunning pictures of this previously unseen natural wonder.