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)

Storm clouds build over a canola field near Cremona, Alberta, Friday, July 29, 2022. (Photo by Jeff McIntosh/The Canadian Press via AP Photo)

Jockeys and their horses reflect in the water of Laytown Beach during the third race of the day at the Laytown Races in Co Meath, Ireland on Tuesday, September 12, 2023. (Photo by Clodagh Kilcoyne/Reuters)

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)

An areal view of the lake in the form of a heart in Rodgau, near Frankfurt, Germany, Friday, May 24, 2024. (Photo by Michael Probst/AP Photo)

A severe thunderstorm hits Omaha, Neb., on Wednesday, June 12, 2024. (Photo by Chris Machian/Omaha World-Herald via AP Photo)

An elephant eats a snack after performing at Ringling Bros and Barnum & Bailey Circus' “Circus Extreme” show at the Mohegan Sun Arena at Casey Plaza in Wilkes-Barre, Pennsylvania, U.S., April 29, 2016. Elephants take a final bow at Ringling Bros and Barnum & Bailey Circus on Sunday, ending a 145-year spectacle that delighted fans but enraged animal activists, who say the highly publicized retirement is not enough. (Photo by Andrew Kelly/Reuters)