An Afghan woman walks along a street covered with snow on the outskirts of Kabul, Afghanistan February 7, 2017. (Photo by Omar Sobhani/Reuters)

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)

Gray whale feeding at the surface and showing it's baleen. (Photo by Christopher Swann/Biosphoto)

In this Wednesday, November 15, 2012 file photo, a young girl in her colorful dress reaches out to greet a Pakistani policeman securing the road outside Kainat Riaz's home in Mingora, Swat Valley, Pakistan. (Photo by Anja Niedringhaus/AP Photo)

A dancer poses for a photograph as part of the “Dance as Art” photo project in Times Square in New York, on September 22, 2014. (Photo by Carlo Allegri/Reuters)

A street vendor wearing a Santa Claus costume sits next to a girl at the boulevard of Sabana Grande in Caracas, Venezuela December 19, 2016. (Photo by Marco Bello/Reuters)

Mangrove in Walakiri Beach after Sunset in East Sumba, Indonesia in 2018. (Photo by Sarubabel Malau/Rex Features/Shutterstock)

Chinese-American actress Bai Ling attends “The Key” screening at The Real Experimental Film Festival at Laemmle's Music Hall on November 21, 2014 in Beverly Hills, California. (Photo by Barry King/WireImage)