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)

A man arranges a display of cacti during preparations for the RHS Chelsea Flower Show in London, Britain May 21, 2016. (Photo by Neil Hall/Reuters)

People walk with their arms raised as security forces restore order in Nice, France on July 14, 2016. (Photo by SIPA Press/Rex Features/Shutterstock)

A reveller takes part in the Holi Party Festival at Niemeyer Center in Aviles, northern Spain, August 27, 2016. (Photo by Eloy Alonso/Reuters)

Office sеx. (Photo by Orange-Melody/Getty Images)

A train drives along a field at a salt production site at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, November 14, 2017. A saltwater lagoon known as Lake Sasyk-Sivash on Ukraine's Crimea peninsula is the source of a rare resource: pink salt. The mineral is tinted by tiny algae that produce the pigment beta-carotene. Each autumn, seasonal workers collect thousands of tons of pink salt for processing and export. (Photo by Pavel Rebrov/Reuters)

Men soar through the air on a wooden sledge during a traditional Bavarian horn sledge race, known as “Schnablerrennen”, in Gaissach near Bad Toelz, Germany, January 22, 2017. (Photo by Michael Dalder/Reuters)