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.

Jaison Vargas, crocodile tour guide, takes a picture of an American crocodile (Crocodylus acutus) during a tour at the Tarcoles river, in Tarcoles, Garabito municipality, Costa Rica, on March 31, 2022. Crocodile tours in the estuary of the Tarcoles River are a popular attraction for visitors to Costa Rica's Pacific coast, as the area gets back on its feet after being shaken by the pandemic. The river is home to nearly 500 species of birds and some 2,000 American crocodiles, many of which have been named after famous people. (Photo by Luis Acosta/AFP Photo)

Merit Prize Winner: “A Well Earned Rest in the Sahara”. This photo of Moussa Macher, our Tuareg guide, was taken at the summit of Tin-Merzouga, the largest dune (or erg) in the Tadrat region of the Sahara desert in southern Algeria. Moussa rested while waiting for us to finish our 45-minute struggle to the top. It only took ten minutes of rolling, running, and jumping to get back down. The Tadrat is part of the Tassili N'Ajjer National Park World Heritage area, famous for its red sand and engravings and rock paintings of cattle, elephants, giraffes, and rhinos that lived there when the climate was milder. Photo location: Summit of Tin-Merzouga, Tadrat, Tassili N'Ajjer National Park, Algeria. (Photo and caption by Evan Cole/National Geographic Photo Contest)

Will Rosner and a playful humpback whale pose for a selfie. This man is certainly knows how to enjoy life travelling the South Pacific and posing for selfies with a whale. Australian carpenter Will Rosner, 24, from Sydney, Australia, has been travelling the world for the past 18 months but nothing could have prepared him for this incredible postcard moment. Swimming in the pristine waters of the Tonga in the Pacific Ocean Will was lucky enough to have the chance to swim with an entire pod of humpback whales. (Photo by WIll Rosner/Caters News)

Men eat oranges from a push cart along a road as a vehicle travels past them in Karachi January 22, 2015. (Photo by Akhtar Soomro/Reuters)

A tornado builds and travels southwest causing damage near Dean Rd. and 82nd Avenue in Hutchinson, Kan. on Monday, July 13, 2015. (Photo by Sandra J. Milburn/The Hutchinson News via AP Photo)

Daniel Rericha born in 1972 in the Czech Republic. Living in a small town, located near the mountain ridge, from childhood he was inspired by the mountains and fell in love with them. In his spare time he enjoys traveling with his wife. In these travels, he tries to capture in his lens as many beautiful places. His work is imbued with the spirit through the mountains, air and space.

This picture taken on April 5, 2022 shows a train travelling along a bridge past cherry blossoms in Tokyo's Shinagawa district. (Photo by Philip Fong/AFP Photo)