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.

Ex-Pussycat Dolls singer Nicole Scherzinger and The Cuban Brothers perform at the de Grisogono party during the 71st annual Cannes Film Festival at Villa des Oliviers on May 15, 2018 in Cap d'Antibes, France. (Photo by Goff Photos)

Fiji's outside centre and captain Waisea Nayacalevu celebrates scoring his team's first try during the France 2023 Rugby World Cup Pool C match between Wales and Fiji at Stade de Bordeaux in Bordeaux, south-western France on September 10, 2023. (Photo by Christophe Archambault/AFP Photo)

Cast member Ana de Armas poses during a photocall for the film “Hands of stone” out of competition at the 69th Cannes Film Festival in Cannes, France, May 16, 2016. (Photo by Regis Duvignau/Reuters)

An employee collects eggs from inside a dead female sturgeon at the caviar fish farming company “Sturgeon”, the leading French producer, in Saint-Genis-de-Saintonge, France, November 8, 2016. (Photo by Regis Duvignau/Reuters)

Actress Laetitia Casta attends the “The Meyerowitz Stories” screening during the 70th annual Cannes Film Festival at Palais des Festivals on May 21, 2017 in Cannes, France. (Photo by Stephane Mahe/Reuters)

Sara Sampaio attends “The Killing Of A Sacred Deer” screening during the 70th annual Cannes Film Festival at Palais des Festivals on May 22, 2017 in Cannes, France. (Photo by David Fisher/Rex Features/Shutterstock)

“Game of Thrones” star, actress Sophie Turner attends the “X-Men Dark Phoenix” Photocall At Cafe de l'Homme on April 26, 2019 in Paris, France. (Photo by Splash News and Pictures)