World's Largest Cave - Sun Doong Cave

The Sun Doong Cave in Vietnam's Phong Nha-Ke Bang National Park is the (currently) world's largest cave. Known by locals for years, it was only discovered by outsiders in 1991. A group of scientists from the British Cave Research Association discovered the cave while conducting a survey in the area.

The cave is over 5 kilometers long, 200 meters high and 150 meters wide. The mouth of the cave emits a loud whistling sound, as wind is forced from the opening. The locals fear the cave because of this sound.

National Geographic photos of Sun Doong Cave.