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 photographer has captured these eerie images showing the scale of some of Britain's deepest darkest wonders. Mike Deere, from Reading, heads to daunting locations such as abandoned mine shafts, miles of sewer tunnels that snake underneath London and even disused cooling towers. Photo: This incredible picture was taken at the Box Freestone Mine, in Wiltshire. Mike revealed that even experienced map readers would struggle to navigate their way around the seemingly endless tunnels that he and his friends visit. (Photo by Mike Deere/Caters News)

Dharma the Sumatran tiger yawns as members of the public return to Edinburgh Zoo as it opens for the first time following the easing of Scottish Governments lockdown restrictions on June 29, 2020 in Edinburgh, Scotland. Outdoor visitor attractions in Scotland have reopened along with many non-essential retailers after more than three months in lockdown, as Scotland moves into phase 2 of its “route map” for easing coronavirus restrictions. (Photo by Jeff J. Mitchell/Getty Images)

A man with an American flag on his back and a Biden/Harris campaign flag rides an electronic skateboard through Black Lives Matter Plaza in front of the White House on Election Day, November 3, 2020 in Washington, DC. This year's historic presidential election between President Donald Trump, the incumbent, and Democratic nominee Joe Biden begins to come to a close even though final results are not expected for days to come as states take longer to count historic levels of mail-in ballots. (Photo by Samuel Corum/Getty Images)

A propaganda troupe perform a flag- waving routine outside the central railway station in Pyongyang, North Korea on September 27, 2017. (Photo by Ed Jones/AFP Photo)

A demonstrator with a Palestinian flag painted on her face takes part in a march to express solidarity with Palestinians in Gaza, in Beirut, Lebanon on October 13, 2023. (Photo by Mohamed Azakir/Reuters)

An armed tribesman loyal to Houthis steps on a US flag during an anti-USA and anti-Israel rally, in Sana'a, Yemen, 29 January 2024. (Photo by Yahya Arhab/EPA/EFE)

A Ukrainian serviceman stands on a flag of Russia's mercenary group Wagner near the Russian border in Sumy region, Ukraine on August 13, 2024. (Photo by Viacheslav Ratynskyi/Reuters)