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.

Camp director and “duck walk” inventor (Rodin Gilbert Flores, 2nd R) teaches aspiring beauty queens how to “duck walk” at a beauty boot camp in Manila in this picture taken on March 8, 2015. From wading in muddy Philippine rice paddies, former housemaid Janicel Lubina now struts down runways for the country's top designers, and is poised to be crowned among the world's most beautiful. Lubina is a star recruit in one of Manila's beauty pageant boot camps, where shy, lanky teenage girls from remote farming provinces are transformed into poised Barbie dolls who can preach about world peace in six-inch heels. (Photo by Noel Celis/AFP Photo)

(L-R) Diana Burkot, Maria Alyokhina and Olga Borisova perform at the concert of the anti-cremlin and feminist band p*ssy Riot at Funkhaus Berlin on May 12, 2022. The 33-year-old Alyokhina had only recently fled Russia. Based on the book “Riot Days” by Alyokhina, the “p*ssy Riot Anti-War Tour” presented a performance project consisting of music, theater and video recordings. 19 performances have been announced for the tour. The punk band has been a thorn in the side of the Russian government for years. (Photo by Bernd von Jutrczenka/dpa)

The first jaguar litter since 1975 was born at the Milwaukee County Zoo to Stella and Pat on November 13, 2013. The litter was on public display for the first time on March 13 when the jaguar baby's names were released. Belize schoolchildren named one Zean, which is the end of Belizean, and a public contest named the other B'alam, which means "great and powerful king" in Mayan. Photo: Stella the mother and her cub Zean rest together at The Milwaukee County Zoo. (Photo by Rick Wood)

“Ary Borges and his family live in southern Brazil like most families the Borges' love animals and have an array of cats living in their home. The only difference between the cats owned by the Borges family and the cat that is cuddled up on your lap as you read this is the Borges' cats weigh over 700 pounds and could kill you just as soon as look at you. The Borges family shares their home with nine tigers, two lionesses, a chimp and a Chihuahua”. – Amanda Schiavo via Latin Times. Photo: The Borges' family pet dog, Little, is placed on the back of Tom, their tiger, for a photo to be taken, in Maringa, Brazil, Friday, September 27, 2013. (Photo by Renata Brito/AP Photo)

This Thursday, January 22, 2015 photo made with a long exposure shows the glow from a Noctiluca scintillans algal bloom along the seashore in Hong Kong. The luminescence, also called Sea Sparkle, is triggered by farm pollution that can be devastating to marine life and local fisheries, according to University of Georgia oceanographer Samantha Joye. Noctiluca itself does not produce neurotoxins like other similar organisms do. But its role as both prey and predator tends can eventually magnify the accumulation of toxins in the food chain, according to R. Eugene Turner at Louisiana State University. (Photo by Kin Cheung/AP Photo)

This undated handout photograph released by Stony Brook University/ Louisiana State University on March 2, 2018, shows an Adélie penguin looking at a drone at breeding colony on Heroina Island, Danger Islands, Antarctica. A thriving “hotspot” of some 1.5 million Adelie penguins has been discovered on the remote Danger Islands in the east Antarctic, surprised scientists announced on March 2, 2018. (Photo by Rachael Herman/AFP Photo/Louisiana State University AND Stony Brook University)

A Hindu holy man on his way to the annual holy dip at Gangasagar, gestures towards a visitor as he rests at a transit camp in Kolkata, India, Wednesday, January 6, 2016. Thousands of Hindu pilgrims are expected to take the annual holy dip at Gangasagar, where the Ganges River reaches the Bay of Bengal, on the auspicious Makar Sankranti festival day that falls on Jan.14. (Photo by Bikas Das/AP Photo)