The largest cave in the world

Son Doong Cave

The Son Doong Cave in Vietnam's Quang Binh Province is said to be 5.5 miles long, 650ft wide, and 500ft tall. The cave was created 2 - 5 million years ago by river water eroding limestone underneath a mountain. Son Doong cave (Vietnamese: Hang Son Doong) is the world's largest cave, located in Quang Binh province, Vietnam.

It had lain undetected beneath the Annamite Mountains in a remote part of central Vietnam for millions of years until one day in 1991 when a local farmer stumbled across it and sought shelter there from a storm.

But Ho Khanh's subsequent attempts to get back to the enormous cave he'd found were unsuccessful, so he forgot about it and went on with his job until years later when a group of British cavers asked for his help in finding it.

In 2009 they got lucky, and the Son Doong Cave was - at 5.5 miles long and 650ft wide - officially confirmed as the world's largest cave, five time the size of Malaysia's Deer Cave, which had held the title until then.

Map of Son Doong cave

Son Doong Cave: The largest cave in the world open for visitors

The largest cave in the world will soon open for tourists. The only around 20 years ago in Vietnam Son Doong cave discovered will initially be accessible to visitors only tentatively.

The tourism authority in the province of Quang Binh allowed from February to August of next year, visitors only small expeditions, each with up to eight participants. "After that we will decide whether we go to the cave on a regular basis," the deputy director, Nguyen Van Ky said. "We will investigate whether the visits have negative environmental consequences."

The tours have about the Vietnamese provider Oxalis be booked. The've significantly more requests than seats for the coming year. According Oxalis may 2014 a total of only 220 visitors in the cave.

 The tourists camp in the Son Doong cave

 Waterfall in the Son Doong cave 

River in the Son Doong cave

A tour costs U.S. $ 3,000

The expedition is not for the inexperienced. Son Doong located in National Park Phong Nha Ke Bang, about 500 kilometers south of the capital Hanoi. Visitors have to walk 17 kilometers to the cave, according to the Tourism Authority. The expedition begins after a night spot.

In the cave are unusual rock formations and pools and a unique flora and fauna to see, Nguyen said. A tour costs U.S. $ 3,000 per visitor. The National Park is recognized by the UN cultural organization Unesco since 2003 as a World Heritage Site.

Natives of the region in central Vietnam near the border with Laos had discovered the cave with an underground river in 1991. 2009, British scientists took a first expedition.

They found a 6481-meter-long cave, as the researcher Howard Limbert reported . It is partly 150 meters wide and 200 meters high, making it larger than the previously largest known cave in the world in Malaysia, the Deer Cave in Borneo.

DOCUMENTARY VIDEO by National Geographic Channel:

The World's Biggest Cave

National Geographic presents The World's Biggest Cave, a TV special that gives us a close-up look at Son Doong, a huge recently-discovered underground labyrinth in Vietnam.