Son Doong Cave, located in Quang Binh Province, Vietnam, is the largest cave in the world. It covers 3,840,000 cubic meters. It is more than five kilometers long, 200 meters high, and 150 meters wide.
Its name means "Cave of the Mountain River" in Vietnamese. It was formed in soluble limestone, making it a solutional cave.
The cave was discovered by a local man named Ho Khanh in 1991 when he was out hunting. However, local people did not enter the cave due to the whistling sound of wind and the roar of a rushing stream in the cave making terrifying sounds. Only in 2009 did a group of cavers enter.
The cave contains some of the tallest known stalagmites in the world, reaching up to 70 meters tall. It consists of two dolines (areas with collapsed ceilings). This allows sunlight to enter the cave so that foliage can grow. This makes it home to many animals, including monkeys, flying foxes, and more. The cave has its own climate suitable for plant and algae growth.
Reaching the cave requires two days of intense jungle trekking and river crossings. Tours to the cave have been open to the public since 2013.