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.

Firefighters watch as an air tanker drops retardant while battling the Ferguson fire in the Stanislaus National Forest, near Yosemite National Park, California on July 21, 2018. A fire that claimed the life of one firefighter and injured two others near California's Yosemite national park has almost doubled in size in three days, authorities said Friday. (Photo by Noah Berger/AFP Photo)

One-month-old cubs given birth by giant panda “Su Shan” are seen at Shenshuping giant panda base on August 17, 2021 in Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province of China. (Photo by He Haiyang/VCG via Getty Images)

“The harp seal or saddleback seal is a species of earless seal native to the northernmost Atlantic Ocean and adjacent parts of the Arctic Ocean. Newborn pups weigh around 11 kilograms (24 lb) and are 80–85 centimetres (31–33 in) long. After birth, the mother only feeds that pup. During the 12 day nursing period, the mother does not eat, losing up to 3 kilograms (7 lb) per day. Harp seal milk contains up to 48% fat, so pups gain over 2.2 kilograms (4.9 lb) per day. During this time, the juvenile's “greycoat” grows in beneath the white neonatal coat, and it weighs 80 pounds (36 kg)”. – Wikipedia

Photo: A harp seal pup lies on an ice floe in the Gulf of Saint Lawrence March 24, 2008 in Charlottetown, Canada. (Photo by Joe Raedle/Getty Images)

In this February 19, 2017 photo, a statue of the Death Saint stands inside Mercy Church as Juan Carlos Avila Mercado gives a service, on the edge of Mexico City's Tepito neighborhood. “She chooses them and has always been with us”, said Avila, who says he is a Catholic priest, but who is not listed among the archdiocese's priests. “We are born and we die with death”. (Photo by Marco Ugarte/AP Photo)

A woman lays dead outside the Redemption Hospital on Saturday September 20, 2014 in Monrovia, Liberia. Ebola patients come to the hospital, which has become a transfer and holding center to intake Ebola patients, but there is no space and some die while waiting outside. Redemption is located in one of the poorest neighborhoods of Monrovia that locals call "New Kru Town”. Health workers are overwhelmed with a constant stream of new patients since the Ebola outbreak. (Photo by Michel du Cille/The Washington Post)

Girls dressed in “Hanfu”, or Han clothing, prepare for an event to mark the traditional Qixi festival, the Chinese equivalent of Valentine's Day, at a park in Beijing, China, August 7, 2019. Chinese for “Han clothing”, “Hanfu” is based on the idea of donning costumes worn in bygone eras by China's dominant Han ethnicity. Some of the most popular styles are from the Ming, Song and Tang dynasties. Hanfu enthusiasts doubled to two million in 2018 from a year earlier, according to a survey by Hanfu Zixun, a popular community account on the Wechat social media platform. (Photo by Jason Lee/Reuters)

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)