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 Vietnamese artist acting as a medium, performs the “Hau Dong” ritual at Viet Theatre in Hanoi January 16, 2016. For the first time, Vietnamese drama director Viet Tu has brought the ritual from religious temples to the theatre partly to draw tourists. The “Hau Dong” is a ritual where a medium puts on special costumes and tells stories of gods and heroes while being accompanied by “Chau Van” music, as part of the act of Dao Mau – the worship of mother goddesses in Vietnam. It is believed that the medium is capable of having a direct contact with spirits during the ritual. (Photo by Reuters/Kham)

Military enthusiasts take part in a re-enactment of the World War II battle of Stalingrad at the “Stalin Line” memorial, near the village of Goroshki, Belarus, February 27, 2016. (Photo by Vasily Fedosenko/Reuters)

Rebelling against political propaganda, acclaimed photographer Antanas Sutkus embarked on a life-long journey to capture the everyday scenes around him. Antanas Sutkus, born in 1939, studied journalism at Vilnius University in the late 1950s before becoming disillusioned by the confines of the Soviet-controlled press. He began taking photographs instead, and soon co-founded the Lithuanian Association of Art Photographers. Here: The first Lithuanian bikers, 1974. (Photo by Antanas Sutkus)

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)

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

A homeless man rests on the side of a street at the old quarter of Yemen's capital Sanaa November 27, 2015. (Photo by Khaled Abdullah/Reuters)

A man smiles as he carries firewood he bought on a street amid ongoing fuel and cooking gas shortages in Yemen's capital Sanaa December 2, 2015. (Photo by Khaled Abdullah/Reuters)