Taken by photographer, Denis Budkov, 33, the Plosky Tolbachik is one of a cluster of volcanoes located in the Kamchatka Peninsula in the far east of Russia. After taking a lucky group of tourists to the crater of the flat volcano, the Russian photographer managed to get less than 300 metres away from the spurting jets of lava. Photo: The underground entrance to the volcano resembles a scene from the latest Hobbit movie. (Photo by Denis Budkov/Caters News)

The series of shots show the bare steel infrastructure of the Bushfield army training camp near Winchester which was in operation during World War Two and was used to train Royal Green Jackets recruits in the sixties. The spectacular images were taken by an urban explorer who wished to remain anonymous. Here: A railway siding in Wiltshire, UK where ammunition was transferred by tunnel to an underground storage facility. (Photo by MediaDrumWorld.com)

Sam Warren climbs in to a prototype combat vehicle during the PrepperCon expo Friday, April 24, 2015, in Sandy, Utah. Hundreds of survivalists and “preppers” are gathering in the Salt Lake City suburb of Sandy for the first annual PrepperCon, featuring demonstrations of underground bunkers, food storage, and armored vehicles. (Photo by Rick Bowmer/AP Photo)

A man reacts to being warned by a British Transport Police officer for not wearing a face mask at King's Cross underground station, London, England on October 8, 2020. (Photo by Jonathan Brady/PA Images via Getty Images)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

A Palestinian man sits on a damaged car following Israeli airstrikes on Jabaliya refugee camp, northern Gaza Strip, Thursday, May 20, 2021. Heavy airstrikes pummeled a street in the Jabaliya refugee camp in northern Gaza, destroying ramshackle homes with corrugated metal roofs nearby. The military said it struck two underground launchers in the camp used to fire rockets at Tel Aviv. (Photo by Khalil Hamra/AP Photo)

“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)