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.

Fans bath in the mud during the “Woodstock Festival Poland” on August 3, 2017 in Kostrzyn Nad Odra, Poland. The annual 3 day music festival organised by The Great Orchestra of Christmas Charity, one of Polands most respected charities aims at spreading awareness about drugs and violence. Przystanek Woodstock in Poland is the largest Europe open air festival. (Photo by Music/Alamy Stock Photo)

People fancy dressed as “Catrina” take part in the “Catrinas Parade” along Reforma Avenue, in Mexico City on October 22, 2017. Mexicans get ready to celebrate the Day of the Dead highlighting the character of La Catrina which was created by cartoonist Jose Guadalupe Posada, famous for his drawings of typical local, folkloric scenes, socio- political criticism and for his illustrations of “skeletons” or skulls, including La Catrina. (Photo by Ronaldo Schemidt/AFP Photo)

Revellers dressed in mock military garb take part in the “Els Enfarinats” battle in the southeastern Spanish town of Ibi on December 28, 2017. During this 200-year-old traditional festival participants known as Els Enfarinats (those covered in flour) dress in military clothes and stage a mock coup d'etat as they battle using flour, eggs and firecrackers outside the town hall as part of the celebrations of the Day of the Innocents. (Photo by Jaime Reina/AFP Photo)

Young artists perform at the presentation of clowns in a hall of the Arts Palace during the first clown festival in Belarus in Bobruisk, some 150 km from Minsk, Belarus, 01 April 2018. About 60 clowns from Belarus and Russia gathered to entertain spectators. For 1 day Bobruisk became a capital of Jokes and Humour. Theaters of clownery, mime-theaters, individual performers of humorous genre, stilts and hospital clowns performed on a stage of the Palace of Arts. (Photo by Tatyana Zenkovich/EPA/EFE)

Iraqi women practice at the sports club in Diwaniya, Iraq on November 10, 2018. On the blue mats of the al-Rafideen Club in the conservative city of Diwaniya, some 180 km (110 miles) south of Baghdad, some 30 female wrestlers, some still wearing headscarves, train three times a week. When a big competition comes up, they train every day. (Photo by Alaa Al-Marjani/Reuters)

People clean up debris at a traditional market damaged by flood after torrential rain on August 09, 2022 in Seoul, South Korea. The heaviest rainfall in 80 years has pounded Seoul and surrounding regions, leaving seven people dead and six others missing, as well as flooding homes, vehicles, buildings and subway stations, government officials said. (Photo by Chung Sung-Jun/Getty Images)

Race fans watch from the grandstands as Air Force One circles the Daytona International Speedway as President Donald Trump makes his arrival to attend the NASCAR Daytona 500 auto race at Daytona International Speedway, Sunday, February 16, 2020, in Daytona Beach, Fla. (Photo by Jim Topper/AP Photo)