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.

These photographs appear to show a spectacular underwater world making it ideal for scuba divers – in central Europe. Twelve metres of water covers trees, footpaths, benches and bridges that are usually accessible throughout the year. Visitors to the Green Lake in Tragoess, Austria, that is normally only one metre deep, can leisurely stroll around the picturesque lagoon. Photo: A diver crossing a bridge in the flood water. (Photo by Solnet/The Grosby Group)

Kubra Korkut of Turkey in action against Viktoriia Safonova of the Russian Paralympic Committee during Class 7 Group B Women's Singles Table Tennis Match on day 2 of the Tokyo 2020 Paralympic Games at Tokyo Metropolitan Gymnasium on August 26, 2021 in Tokyo, Japan. (Photo by Ivan Alvarado/Reuters)

Lieke Martens of Netherlands is tackled by Andi Sullivan of USA during the FIFA Women's World Cup Australia & New Zealand 2023 Group E match between USA and Netherlands at Wellington Regional Stadium on July 27, 2023 in Wellington / Te Whanganui-a-Tara, New Zealand. (Photo by Amanda Perobelli/Reuters)

England's Rachel Daly celebrates scoring their side's sixth goal of the game with team-mates during the FIFA Women's World Cup 2023, Group D match at the Hindmarsh Stadium, Adelaide, Australia. Picture date: Tuesday August 1, 2023. (Photo by Hannah Mckay/Reuters)

Denmark's forward #10 Pernille Harder celebrates scoring her team's first goal during the Australia and New Zealand 2023 Women's World Cup Group D football match between Haiti and Denmark at Perth Rectangular Stadium in Perth on August 1, 2023. (Photo by Luisa Gonzalez/Reuters)

A group of caimans sit on the banks of the almost dried up Bento Gomes River in the Pantanal wetlands near Pocone, Mato Grosso state, Brazil, Wednesday, November 15, 2023. Amid the high heat, wildfires are burning widely in the Pantanal biome, the world's biggest tropical wetlands. (Photo by Andre Penner/AP Photo)

Belgium fan wears a devil mask attends the Qatar 2022 World Cup Group F football match between Croatia and Belgium at the Ahmad Bin Ali Stadium in Al-Rayyan, west of Doha on December 1, 2022. (Photo by Stephane Mahe/Reuters)