On the western side of Mount Hood lies the longest glacier cave system in the contiguous United States. In 2012, these caves were mapped to a combined length of 7,166.8 feet by cave explorers Brent McGregor and Eddy Cartaya. Currently, the total passage length is hundreds of feet less. Glaciers are frozen rivers; they are always moving and changing... (Photo and caption by Josh Hydeman)

Carlos Melendez prepares to feed his pet squirrel “Colita” in downtown San Salvador January 29, 2015. (Photo by Jose Cabezas/Reuters)

An Orthodox activist (Right) clashes with a gay rights campaigner during a protest outside of the State Duma, Russian Parliament's lower chamber, in downtown Moscow, January 22, 2013. (Photo by Ilya Pitalev/RIA Novosti)

A young woman wearing no trousers hits the ski slopes at a ski resort in Xuzhou, in east China's Jiangsu province on January 13, 2015 in a promotional effort to equal “No Pants Subway Ride”, which was marked on January 11 this year. The promotional “No Pants Subway Ride” stunt on January 11 was held as commuters in some 60 cities around the world braved public transportation in their undies, which has gone global since its first staging by US group Improv Everywhere in New York in 2002. (Photo by AFP Photo)

A student participates in celebrations ahead of the Janmashtami festival, which marks the birth anniversary of Lord Krishna in Mumbai, India, August 23, 2016. (Photo by Danish Siddiqui/Reuters)

British reality stars Kerry Katona and Michelle Heaton Relax poolside with their families in Bridgwater, Somerset, England on August 30, 2016. Kerry Katona was wearing a “Swag” t-shirt before stripping down to a red bikini. Kerry looked to be having a great time with Michelle and family. (Photo by FameFlynet UK)

Sergei Bobkov, 59, paints Siberian cedar nut oil onto a life-size sculpture of Pallas's Cat, also known in Russia as Manul Cat, which he made from Siberian cedar wood shavings using more than 700 thousand pieces over four years, in the village of Kozhany, southwest of the Siberian city of Krasnoyarsk, Russia, April 28, 2017. (Photo by Ilya Naymushin/Reuters)

Fans are seen at the 143rd Kentucky Derby on May 6, 2017 in Louisville, Kentucky. (Photo by Michael Hickey/Getty Images)