Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

A man stands on a mountain summit as he looks over the Inntal valley in the western Austrian village of Gnadenwald, Austria on July 18, 2017. (Photo by Dominic Ebenbichler/Reuters)

The dramatic moment lightning strikes the sea at Portland in Dorset in southwest England on October 24, 2022. Thundery weather and a dramatic Lightning storm pictured last night at Portland Bill. (Photo by CharlotteChapman/Bournemouth News)

Horses eat hay and rest on straw at a stud farm in Wehrheim near Frankfurt, Germany, Tuesday, December 5, 2023. (Photo by Michael Probst/AP Photo)

A model stands in a light backstage after presenting the collection by Russian designer Alena Akhmadullina at The Russian State Library, one of the three national libraries of Russia, the largest library in the country, largest in Europe, in Moscow, Russia, on Wednesday, November 29, 2023. (Photo by Alexander Zemlianichenko/AP Photo)

This aerial photograph taken on January 27, 2024 shows a camel in the desert of Samawa in Iraq's southern province of al-Muthanna. (Photo by Hussein Faleh/AFP Photo)

A man walks along a corridor at a hotel in Singapore on February 7, 2024. (Photo by Edgar Su/Reuters)

Event entertainer Holly Egan poses with a guitar using an angle grinder as Kevin Jay and Nigel Cox spin burning steel wool, sending sparks flying under the A13 in Essex, UK on April 4, 2024. (Photo by Kevin Jay/Picture Exclusive)