A woman wearing a mask walk in a street in a Yonghegong Lama temple compound seen shrouded in smog in Beijing, China, 30 November 2015. Beijing issued an orange alert for heavy smog 30 November, the highest level this year. Authorities in the Chinese capital warned of 'severe pollution' and advised the capital's 20 million inhabitants to stay indoors. (Photo by How Hwee Young/EPA)

Waves triggered by Typhoon Hato are seen in Hong Kong, China on August 23, 2017. A powerful typhoon barreled into Hong Kong on Wednesday, forcing offices and schools to close and leaving flooded streets, shattered windows and hundreds of canceled flights in its wake. Typhoon Hato came within 60 kilometers (37 miles) of Hong Kong, close enough to be considered a direct hit under Hong Kong's storm warning system. It was headed toward the western side of mainland China's Pearl River Delta. (Photo by Tyrone Siu/Reuters)

Two women jump into a frozen pond as they compete in the Polar Plunge at Frozen Dead Guy Days in Nederland, Colorado March 14, 2015. The winter festival in the small mountain town commemorates the 1994 discovery of the corpse of Bredo Morstol, which is now housed in a shed on dry ice above the town. (Photo by Rick Wilking/Reuters)

A bulldog dressed as Marilyn Monroe poses for a photograph during the annual Tompkins Square Halloween Dog Parade in the Manhattan borough of New York City, October 24, 2015. (Photo by Stephanie Keith/Reuters)

A woman lies to pose for her souvenir picture on the glass sightseeing platform on Shilin Gorge in Beijing, China, May 27, 2016. (Photo by Kim Kyung-Hoon/Reuters)

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)