Roof-topping enthusiast Daniel Lau takes a selfie with high-rise buildings down below as he stands on the top of a skyscraper in Hong Kong, China on August 15, 2017. A craze that began in Russia has now taken hold in Hong Kong, one of the world's most vertical cities. Mr Lau said he had been inspired by Russian climbers and that he was unafraid of the vertiginous heights he scales. (Photo by ImagineChina/Rex Features/Shutterstock)

Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

British theoretical physicist Stephen Hawking, Cambridge University Professor and Fellow, circa 1985. Stephen Hawking, the brightest star in the firmament of science, whose insights shaped modern cosmology and inspired global audiences in the millions, has died aged 76. (Photo by Gemma Levine/Getty Images)

In this photo taken on March 11, 2019 an Afghan street vendor selling oranges waits for customers on a rainy day on the roadside in Jalalabad. (Photo by Noorullah Shirzada/AFP Photo)

Revellers out in Blackpool, Lancashire, United Kingdom on New Year's Eve, December 31, 2018. (Photo by Lorne Campbell/Guzelian)

A first white-handed gibbon infant born at the Skopje Zoo is seen with his mother in Skopje, North Macedonia on May 9, 2019. (Photo by Ognen Teofilovski/Reuters)

A member of the Pakistani Anti-Narcotic Force (ANF) takes a selfie beside a pile of burning drugs and liquor during a ceremony at the Kacha Ghari army firing range, on the outskirts of Peshawar on October 16, 2018, after the contraband was seized in raids across the province. (Photo by Abdul Majeed/AFP Photo)

A local farmer Theophilus Mwendwa runs through a swarm of desert locusts to chase them away in the bush near Enziu, Kitui County, some 200km east of the capital Nairobi, Kenya, 24 January 2020. Large swarms of desert locusts have been invading Kenya for weeks, after having infested some 70 thousand hectares of land in Somalia which the United Nations Food and Agriculture Organisation (FAO) has termed the “worst situation in 25 years” in the Horn of Africa. FAO cautioned that it poses an “unprecedented threat” to food security and livelihoods in the region. (Photo by Dai Kurokawa/EPA/EFE)