Smithsonian National Zoo biologist Leigh Pitsko releases a male lion cub for its swim test in the zoo habitat moat, in Washington May 6, 2014. Four, unnamed ten-week old lion cubs were tested today for their ability to swim and remove themselves from their zoo habitat moat. (Photo by Gary Cameron/Reuters)

A man and his dog wade through a flooded road in Vila Velha, Espirito Santo state, Brazil, on December 27, 2013. At least 44 people have died and more than 60,000 have been left homeless following torrential rains over the past few weeks in southeast Brazil. (Photo by Yasuyoshi Chiba/AFP Photo)

In this photo taken on Wednesday, February 17, 2016, a volunteer fighter with the Syrian Government forces sits atop a tank in the province of Raqqa, Syria. In recent weeks, Syrian government forces captured dozens of villages and towns across the country. (Photo by Alexander Kots/Komsomolskaya Pravda via AP Photo)

The US Navy Blue Angels numbers 5 and 6 fly below Sean Tucker (above) as he pilots the Oracle Challenger III over San Francisco, California as part of a practice run for Fleet Week on October 6, 2016. (Photo by Josh Edelson/AFP Photo)

Residents wade across floodwaters after a week typhoon Koppu battered Calumpit town, Bulacan province, north of Manila October 24, 2015. Typhoon Koppu, that dumped heavy rains on the northern Philippines, killing 58 people as it flattened houses and destroyed crops, was petering out on Wednesday, weather officials said. (Photo by Romeo Ranoco/Reuters)

A pilot steers his helicopter at night over Rio de Janeiro, Brazil, less than two weeks before the start of the Rio 2016 Olympic Games, July 23, 2016. Picture taken July 23, 2016. (Photo by Pawel Kopczynski/Reuters)

A man takes a shower on a street from water coming from a drainpipe as it rains in Havana, Cuba, Wednesday, July 27, 2016. During the last couple of weeks short but intense tropical downpours have been coming down of Havana every afternoon. (Photo by Desmond Boylan/AP Photo)

People take part in the Million Mask March anti-establishment protest at Trafalgar Square in London on November 5, 2020, on the first day of a four week national lockdown for England. (Photo by Aaron Chown/PA Images via Getty Images)