Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

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)

Climbers “painted” the Matterhorn red this week to celebrate a special anniversary. A group of mountaineers left red beacons along the route of the famous climb, which is one of the highest mountains in the Alps, and as nightfall came the imposing mountain came alive with colour. The event was organised by clothing brand Mammut to celebrate the 150th anniversary of the first explorers to scale the mountain. (Photo by MSN UK/Mammut)

This watering hole is the social hub of the veldt; the scrubby grasslands that stretch across Namibia. The scorched earth supports sometimes fragile populations of magnificent wildlife – from endangered predators to plentiful herds of game. But these gentle giraffes and elephants need to be careful: lions don’t sleep at night, they hunt! The spectacular starscape above southern Africa is unchanged since explorers first mapped the continent. The photographer, Pietro Olivetta from Italy, said he had to be patient to capture these shots – but it was worth the wait. (Photo by Pietro Olivetta/Caters News)

Polar frame, by Dmitry Kokh, Russia. When Kokh’s boat approached the small island of Kolyuchin in the Russian High Arctic, which had been abandoned by humans since 1992, he was surprised to spot movement in one of the houses. Binoculars revealed polar bears – more than 20 in total – exploring the ghost town. Dmitry used a low-noise drone to document them. (Photo by Dmitry Kokh/Wildlife Photographer of the Year 2022)

Russian Prime Minister and presidential candidate Vladimir Putin speaks during a rally after Putin claimed victory in the presidential election at the Manezhnya Square March, 4, 2012 in Moscow, Russia. Exit polls showed Putin had over 60 percent of the vote according to state television in an election that has been alleged to be marred by widespread violations. (Photo by Oleg Nikishin/Epsilon/Getty Images)

The second and final qualification motor (QM-2) test for the Space Launch System's booster, June 28, 2016, at Orbital ATK Propulsion Systems test facilities in Promontory, Utah. During the Space Launch System flight the boosters will provide more than 75 percent of the thrust needed to escape the gravitational pull of the Earth, the first step on NASA's Journey to Mars. (Photo by Bill Ingalls/NASA)

Getting her tongue pierced was “exciting and scary” says a teen who succumbed to pressure from her best friend in Austin, Texas, February 22, 2008. This image is featured in National Geographic's exhibition “Women of Vision: National Geographic Photographers on Assignment”, on view at the Palm Beach Photographic Centre, Jan. 22 - Mar. 22, 2015. (Photo by Kitra Cahana/National Geographic)