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.

Pole dancers in Mexico have taken to the streets to celebrate their sport and show others the skills involved. The Pole Dance National Day celebration saw pole dancers gather in parks, outdoor gyms and on streets, using street lamps, sign posts and other objects to put on displays across Mexico City. Photo: A woman performs a pole dancing routine on a pedestrian bridge during the national day celebration of “Urban Pole” dance in Monterrey June 8, 2014. (Photo by Tomas Bravo/Reuters)

Protester Lauren Digioia wears police tape during an Occupy Wall Street protest in Union Square on March 19, 2012 in New York City. Protesters affiliated with the movement are gathering in Union Square today following 73 arrests at a six-month anniversary rally at Zuccotti Park over the weekend. (Photo by Mario Tama/Getty Images)

“A girl arrives at the parking lot wearing tiny leather shorts and sits on the back of a bike with a horse power of more than 1,000 CC. Next to her a man gets ready to ride, wearing a skeleton mask. It’s more than a fashion show, it’s an extravaganza on two wheels along Chinese roads”. – Carlos Barria. Photo: A couple rides their motorcycle at the Qian Dao Lake rally, on May 11, 2013. (Photo by Carlos Barria/Reuters)

Corporal of Horse Andy Radford prepares to mount his horse in the parade square at Hyde Park Barracks on April 15, 2011 in London, England. Members of the Household Cavalry gave a behind the scenes tour of many of the duties performed as part of their daily routine, including special preparation ahead of the forthcoming Royal Wedding. The Household Cavalry will perform several ceremonial duties during the summer, including the Royal Wedding on April 29, and the Queen's Birthday Parade (Trooping the Colour) in June. (Photo by Dan Kitwood/Getty Images)

Casket of Leibby Kletzky, a murdered eight-year-old boy who went missing from the Hasidic neighborhood of Borough Park, Brooklyn is carried during a procession on July 13, 2011 in New York City. After a two day search Kletzky's dismembered body was found partially in a suitcase inside a dumpster and partially in a refrigerator in a nearby apartment. Police detectives have taken Levi Aron, 35, into custody in connection to the killing. (Photo by Ramin Talaie/Getty Images)

People view artist David Byrne's installation "Tight Spot" beneath Manhattan's High Line park on September 27, 2011 in New York City. The 48-foot by 20-foot inflatable globe is squeezed beneath the steel support framework of the High Line and is accompanied with a rumbling audio soundtrack created by distorting Byrne's voice. (Photo by Mario Tama/Getty Images)

U.S. President elect Barack Obama kisses his wife Michelle as Vice-President elect Joe Biden (right) embraces his wife Jill after Obama gave his victory speech during an election night gathering in Grant Park on November 4, 2008 in Chicago, Illinois. (Photo by Scott Olson/Getty Images)