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.

People enjoy a bath in hot kvass, a traditional fermented beverage made from rye bread, during the sauna marathon near Otepaa, Estonia, February 6, 2016. Participants have to track down and visit the given saunas in the Otepaa area as fast as possible. (Photo by Ints Kalnins/Reuters)

Never before was there a car designed exclusively for handicapped people that can only move around in a wheelchair. In the past, such people had to rely on others to drive them. Thus, it was impossible to be spontaneous and drive somewhere on a whim. Now, however, a completely revolutionary vehicle has been invented. Kenguru electric car allows for the person to roll into the back of it right on their wheelchair, strap in, and start driving. Though this vehicle might not be very fast with the maximum speed of 25 mph, it is will certainly make the lives of countless people much easier. (Photo by Kenguru.com)

Vendors wait for customers at a wholesale vegetable market in Dhaka on September 4, 2022. (Photo by Munir Uz Zaman/AFP Photo)

People cross the street in central Pyongyang, North Korea May 4, 2016. (Photo by Damir Sagolj/Reuters)

Police officers display their AI-powered smart glasses in Luoyang, Henan province, China on April 4, 2018. (Photo by Reuters/China Stringer Network)