High-rise buildings are partly covered by heavy fog at Hong Kong's Victoria Harbour Monday, March 20, 2017. Fog blanketing Hong Kong is common in springtime and may greatly affect shipping and aviation. (Photo by Vincent Yu/AP Photo)

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)

Catholic faithfuls hold figurines of baby Jesus during a religious procession on Holy Innocents Day in Antiguo Cuscatlan, El Salvador, December 28, 2016. (Photo by Jose Cabezas/Reuters)

A soldier of the French Foreign Legion holding his regiment's banner at Bar Hacheim in Libya, circa 1940. (Photo by Three Lions). P.S. All pictures are presented in high resolution.

A Cambodian girl goes through the garbage dump looking for things to recycle in order to survive July 26, 2003 in Phnom Penh, Cambodia. Rampant corruption in this impoverished country has lead to extreme poverty with many Cambodians living below the poverty line. (Photo by Paula Bronstein/Getty Images)

Father Christmas reading with three young children. (Photo by Spencer Arnold/Getty Images). Circa 1915

Tokyo Rainbow Pride 2015, at Yoyogi park-Shibuya, on April 26, 2015. Some 3,000 lesbian, gay, bisexual and transgender people paraded through Tokyo’s Shibuya district Sunday afternoon to demonstrate their hope that Japanese society will continue to forge ahead with recent moves to embrace equality and diversity. In a nation where prejudice against sexual minorities persists, the annual Tokyo Rainbow Pride parade has sought to counter the trend by openly spotlighting LGBT residents and spreading their voices. But this year, LGBT participants and proponents seemed particularly joyous, emboldened by what they see as a blossoming of LGBT-friendly moves by municipalities and companies. (Photo by Yoshiaki Miura)

A rescue helicopter is shown at the Mount Everest south base camp in Nepal a day after a huge earthquake-caused avalanche killed at least 17 people, in this photo courtesy of 6summitschallenge.com taken on April 26, 2015 and released on April 27, 2015. Rescue teams, helped by clear weather, used helicopters to airlift scores of people stranded at higher altitudes, two at a time. (Photo by Reuters/6summitschallenge.com)