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)

Lawmakers fight around the rostrum during the first session of Ukraine's newly elected parliament in Kiev, Ukraine, December 13, 2012. (Photo by Sergei Chuzavkov/Associated Press)

South Korean university students prepare for an establishment ceremony of the Reserve Officer Training Corps (ROTC) for female cadets at Sookmyung Women's University on December 10, 2010 in Seoul, South Korea. The South Korean defense ministry has agreed to admit women into it's college-based Reserve Officers' Training Program for the first time since the program began in 1963. (Photo by Chung Sung-Jun/Getty Images)

United States Marine Corps Staff Sgt. Jason Itro yells at recruit Nancy Carbins January 15, 2003 after she grabbed another recruit in the pool in an attempt to stay afloat during swim training at the Combat Pool on Parris Island, SC. Under the watchful eyes of swim instructors, recruits are required to swim in full gear and learn limited strokes and breathing to stay afloat. Carbins broke a major rule by grabbing another recruit and submerging them both. (Photo by Stephen Morton/Getty Images)

Migrants rush as they try to get on a train heading to the border with Serbia at the train station of Gevgelija, on the Macedonian-Greek border, on August 9, 2015. Non-EU Serbia's frontier with Hungary, which is in the bloc's passport-free Schengen zone, has become a major crossing point for the huge numbers of migrants entering the EU. (Photo by Dimitar Dilkoff/AFP Photo)

Two men using an electric power saw to fell a tree circa 1940's. (Photo by Keystone View/FPG/Getty Images)

View from the Insta360 360 degree camera in the last decade of November 2023 attached to a satellite launched 500km into outer space. Chinese firm Insta360 say they have achieved “the first fully exposed camera in space” a feat which required a lot of preparation to get X2 ready for the harsh environment. (Photo by South West News Service)

A woman poses for a photo in front of the Wagner Group military vehicle on June 24, 2023 in Rostov-on-Don, Russia. (Photo by Feodor Larin/Anadolu Agency via Getty Images)