Son doong cave is a cave in Phong Nha-Kẻ Bàng National Park, Bố Trạch district, Quảng Bình Province, Vietnam. Currently the biggest known cave in the world, the cave is located near the Laos-Vietnam border. Inside is a large, fast-flowing underground river.
In early August 2013, the first tourist group explored the cave on a guided tour at a cost of US$3,000 each. The group had six members from Australia, Norway, Russia and USA and spent 7 days and 6 nights for the tour. Next exploration trips will be arranged.

Tim Klingender, Director of Aboriginal Art at Sotheby's hangs the painting “Emu Corroboree Man” by Clifford Possum Tjapaltjarri before a record auction of Aboriginal Art July 14, 2005 in Sydney, Australia. The painting is expected to fetch AUD 150,000 – 250,000 (USD 120,000 – 200,000). Sotheby's unveiled a selection of Aboriginal art and artifacts after a tour of New York and London, which will go to auction in Melbourne July 25 2005. The total pre-sales estimate of the collection is AUD 6 million – 8.5 million (USD 5 million – 7 million). (Photo by Ian Waldie/Getty Images)

(R-L) Jean-Jacques Cattier and his son Alexandre Cattier pose with the world largest bottle of Champagne “The Midas” by Armand de Brignac on April 6, 2011 in Berlin, Germany. The Midas is a massive 30-liter vessel and weights exactly 100 pounds. It's like having 40 pieces of the 750ml in one. Number one champagne brand in the world, Armand de Brignac is the luxury Champagne from the award-winning Champagne Cattier chateau of Chigny-les-Roses, France. (Photo by Andreas Rentz/Getty Images)

A camel foams at the mouth as he is whipped by a robot jockey during a race at Nad al-Sheba on December 6, 2006 in Dubai, United Arab Emirates. This is the first season that robotic jockeys have been used to race camels in Dubai. Controversially children from India were used to ride the camels in past seasons. These robot jockeys costing 15000GBP and up, were designed in Geneva and include shock absorbers and GPS tracking systems. The camel's owners control them from their speeding four wheel drives at the side of the track. (Photo by Chris Jackson/Getty Images)

Conjoined twins Angelica (C) and Angelina Sabuco (L) play with child life specialist Allison Brooks during a press conference at the Lucile Packard Children's Hospital at Stanford on October 31, 2011 in Palo Alto, California. Two year-old conjoined twins Angelica and Angelina Subaco who are connected at the chest and abdomen are preparing for separation surgery by Dr. Gary Hartman. The surgery will last between 6 and 8 hours that is followed by three hours of reconstructive surgery for each girl. (Photo by Justin Sullivan/Getty Images)

A ranger of Kenya Wildlife Services (KWS) tries to cover the eyes of 2.5-year-old female Southern white rhino, Elia, to calm down after being shot a tranquilizer from a helicopter during Kenya Wildlife Services (KWS) rhino ear notching exercise for identification at Meru National Park, 350 km from Nairobi, Kenya, on April 5, 2018. (Photo by Yasuyoshi Chiba/AFP Photo)

Paolo Guerrero of Brazil's Internacional reacts after missing an opportunity to score during a Copa Libertadores soccer match against Chile's Palestino in Porto Alegre, Brazil, Tuesday, April 9, 2019. (Photo by Diego Vara/Reuters)

A police officer sings as a hearse drives along a street as part of a campaign sponsored by the Colombian police and a funerary home to raise awareness during the new coronavirus pandemic in Envigado, Antioquia, Colombia, on April 1, 2020. More than 20,000 cases of COVID-19 were registered in Latin America and the Caribbean by Wednesday, according to an AFP tally using information provided by national health authorities and the World Health Organization. (Photo by Joaquin Sarmiento/AFP Photo)