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)

People pass a suitcase as they line up to enter a railway station in Beijing, February 15, 2015. Chinese Ministry of Transport said a total of 2.807 billion trips are expected to be made during the 40-day Spring Festival travel rush, which started on February 4 and will last until March 16, Xinhua News Agency reported. (Photo by Reuters/Stringer)

Ohio State drum major performs during the NCAA football game between the Ohio State Buckeyes and Notre Dame Fighting Irish at Ohio Stadium in Columbus on September 3, 2022. (Photo by Adam Cairns/USA TODAY Sports)

People walk down the street while Hurricane Matthew approaches in Port-au-Prince, Haiti October 3, 2016. (Photo by Carlos Garcia Rawlins/Reuters)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

A girl looks with comic disgust at a guy who falls asleep with a bottle of beer at a party; her friend laughs. (Photo by Edward Corbett/Rex Features/Shutterstock)

A Herero man holds the head of a freshly butchered cow, killed to supply meat for a funeral, 2012. (Photo by Jim Naughten, courtesy of Klompching Gallery, New York)

Jaheel Hyde, of Jamaica, competes in a men's 400-meter hurdles heat at the 2024 Summer Olympics, Monday, August 5, 2024, in Saint-Denis, France. (Photo by David J. Phillip/AP Photo)