An immigrant from Mali rests at the Greek-Macedonian border before an attempt to flee to Macedonia May 13, 2015 village of Idomeni in Kilkis prefecture May 13, 2015. Hundreds of mostly Afghan, Syrian, and African immigrants cross daily from Greece into Macedonia on their way to northern European countries; most of them are turned back by Macedonian border guards. (Photo by Yannis Behrakis/Reuters)

Members of the San Francisco Gay Freedom Day Marching Band and Twirling Corps do their thing down San Francisco's Market Street, June 27, 1982. Police estimate the crowd to be 300,000 for the Lesbian/Gay Freedom Day parade and rally. (Photo by Carl Viti/AP Photo)

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)

Visitors make snowmen beside a pool at a hot spring in Hangzhou, in China's eastern Zhejiang province on January 26, 2018. China's central and eastern regions have been hit by heavy snowfalls in recent days, causing disruptions to flight and train schedules. (Photo by AFP Photo/China Stringer Network)

Maya Nakanishi of Japan competes en route to winning the women's T64 long jump at the World Para Athletics Championships in Dubai on November 11, 2019. (Photo by Christopher Pike/Reuters)

Tourists wear protective masks in Sanur, Bali, Indonesia, 15 March 2020. Indonesia has around 80 active cases of Covid-19. More than 70,000 people worldwide have recovered from coronavirus, nearly half of the total infections recorded since the outbreak began. (Photo by Made Nagi/EPA/EFE)

A fruit bat eats lettuce as it hangs from a rope during a behind the scenes interactive live stream from the Oakland Zoo on April 16, 2020 in Oakland, California. Since the Oakland Zoo has been closed to the public during the shelter in place, they are offering a subscription based service that will feature five weekly behind the scenes live streamed interactive programs that will feature animal keepers and their animals. Viewers are able to interact with the keepers by submitting questions to about the animals. (Photo by Justin Sullivan/Getty Images)