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.

Eurocopter's X³ high-speed hybrid helicopter demonstrator performs, September 6, 2010. The Eurocopter X³ (X-Cubed) is an experimental high-speed compound helicopter developed by Eurocopter (now Airbus Helicopters). A technology demonstration platform for Eurocopter “high-speed, long-range hybrid helicopter” or H³ concept, the X³ achieved 255 knots in level flight on 7 June 2013, setting an unofficial speed record for a helicopter. (Photo by Reuters/HO/Eurocopter/Penna)

In this March 13, 2015 photo, Yohan, 4, from left, Cristian, 7, and Angelo, 6, playfully toss coca leaves into the air, singing: “I have a lot of money, look at all the money I have”, in La Mar, province of Ayacucho, Peru. Hauling cocaine out of the remote valley is about the only way to earn decent cash in this region where a farmhand earns less than $10 a day. Beyond extinguishing young lives, the practice has packed Peru's highland prisons with cocaine backpackers while their bosses evade incarceration. (Photo by Rodrigo Abd/AP Photo)

Isaiah Bowen, right, takes a shot as his dad, Garth Bowen, center, looks on at a basketball hoop in front of the statue of Confederate General Robert E. Lee on Monument Avenue Sunday June 21, 2020, in Richmond, Va. A judge extended an injunction delaying the removal of the statue by the state. The statue had become a focal point for the Black Lives Matter movement in Richmond. (Photo by Steve Helber/AP Photo)

Dr. Adolfo Roitman presents a part of the Isaiah Scroll, one of the Dead Sea Scrolls, inside the vault of the Shrine of the Book building at the Israel Museum on September, 26, 2011. in Jerusalem, Israel. For the first time some of the Dead Sea Scrolls are available online thanks to a partnership between Google and Israel's national museum. (Photo by Lior Mizrahi/Getty Images)

Ukrainian Serviceman Oleksii Hodzenko, aka Godzilla, was a civilian journalist. His father, Sergeant chief Dmytro "Godzilla" Godzenko was killed on March 31, 2016 at 6 a.m. in a mortar attack near the village of Zaitsevo near Horlivka in the Donetsk region. Since then Godzilla "junior" has joined the army, at a frontline position held by Ukraine's 503rd Detached Marine Battalion on February 7, 2022 near Verkhnotoretske, Ukraine. Regional tensions remain high as Russia continues to amass soldiers and military equipment along its border with Ukraine, where large swaths of the Luhansk and Donetsk regions are held by Russian-backed separatists. Russia has also moved roughly 30,000 troops into Belarus, which borders Ukraine to the north. American and European officials say they do not whether Russian President Vladimir Putin has made a decision to invade Ukraine, but have issued a series of warnings about the country's assertive military posture. (Photo by Gaelle Girbes/Getty Images)