“Mr Big Dipper”, Nicholas Roemmelt (Denmark). A stargazer observes the constellation of the Big Dipper perfectly aligned with the window of the entrance to a large glacier cave in Engadin, Switzerland. This is a panorama of two pictures, and each is a stack of another two pictures: one for the stars and another one for the foreground, but with no composing or time blending. (Photo by Nicholas Roemmelt/National Maritime Museum/The Guardian)

Dressers make last minute adjustments to the costumes of dancers performing as horses during a press preview of American artist Nick Cave's first major work shown in Australia, entitled HEARD.SYD in Sydney, November 8, 2016. Over several days the live art performance will feature 30 “horses” dancing to live percussion beats in suits made from coloured raffia plant fibres. (Photo by Jason Reed/Reuters)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

Internally displaced Syrian children stand at the entrance of their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. (Photo by Khalil Ashawi/Reuters)

Dancers perform during the Sambodromo do Brasil jungle party in the Cave stage, Elrow Town at Queen Elizabeth Olympic Park on August 18, 2018 in London, England. (Photo by Ollie Millington/Redferns)

Young women walk through the cave of Saint George during Ashenda festival, at Saint George Church, in Lalibela, Ethiopia, on August 22, 2022. (Photo by Amanuel Sileshi/AFP Photo)

Asia Sawicka as Anastasia IV poses for a photograph prior to a rehearsal of the Circus of Horrors' latest show Voodoo, ahead of Halloween, at the Wookey Hole Caves Theatre near Wells on October 19, 2017 in Somerset, England. (Photo by Matt Cardy/Getty Images)

National Geographic has created “Air, Land & Sea: the 50 greatest wildlife photographs” exhibition. Here: CT4 Crocodile cave on the Salamat river. Set up with Nathan Williamson last chip rain came while we were with the nomads. (Photo by Michael Nichols/National Geographic)