A woman enjoys the sun at Plaka beach on the Aegean island of Naxos, Greece, Friday, May 14, 2021. Greece launched its tourism season Friday amid a competitive scramble across the Mediterranean to lure vacationers emerging from lockdowns. (Photo by Thanassis Stavrakis/AP Photo)

Excited Brits beamed as they grabbed a pint outside in Leeds, United Kingdom on April 17, 2021. Pubs and restaurants with outdoor space have been allowed to reopen as lockdown restrictions are eased in the UK. (Photo by Nb press ltd)

Corey Jurgensen runs along East Henry Avenue wearing an inflatable unicorn costume. Jurgensen has been wearing the costume during runs several times a week to cheer up others during this time of isolation but finds it therapeutic for herself as well to run through her Seminole Heights neighborhood wearing a silly costume, Thursday, April 16, 2020 in Tampa, Fla. (Photo by Martha Asencio Rhine/Tampa Bay Times via AP Photo)

A man pours water on his camel on a hot summer day in Ahmedabad, India, May 18, 2017. (Photo by Amit Dave/Reuters)

A relative performs rituals for a man who died of coronavirus disease (COVID-19), before his cremation at a crematorium in New Delhi, India, November 19, 2020. (Photo by Danish Siddiqui/Reuters)

Two zebras stand so close in Ngorongoro Crater, Tanzania. (Photo by Zhayynn James/Solent News)

Models promote a condom brand at the first Shenzhen s*x Culture Festival on September 21, 2007 in Shenzhen of Guangdong Province, China. The festival aims to increase awareness about reproductive health and popularise s*x education. (Photo by China Photos/Getty Images)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)