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)

Members of the staff wait for the start of the maiden press conference for China's all-girl “boyband” FFC-Acrush in Beijing, China April 28, 2017. Picture taken April, 28, 2017. (Photo by Damir Sagolj/Reuters)

Trainer Lawney Hill poses for a photograph as she wears tights over her face to keep out the cold after taking her horses out on the all-weather gallops in Tetsworth, Britain, March 2, 2018. (Photo by Eddie Keogh/Reuters)

A girl jumps over a campfire while celebrating Ivan Kupala Night, a traditional Slavic holiday not far from Kiev on July 6, 2013. During the celebration, originating in pagan times, people plait wreaths, jump over fires, and swim naked. (Photo by Sergei Supinsky/AFP Photo)

Cosplayers take a break from the convention to check their phones and get coffee during “Anime Boston 2024” at the Hynes Convention Center in Boston, Massachusetts, on March 30, 2024. The convention is organized by the New England Anime Society and celebrates all things Japanese animation, comics and popular culture. (Photo by Joseph Prezioso/AFP Photo)

Assamese girls wearing traditional Mekhela Chadar perform the Bihu folk dance during the Rongali Bihu festival, organized by All Assam Students Union in Guwahati, capital of the north eastern state of Assam, India, Saturday, April 13, 2024. (Photo by Anupam Nath/AP Photo)

Giant 65-foot-long Hot dog artwork by Brooklyn-based artist duo Jen Catron and Paul Outlaw stands on the middle of Times Square in New York City, NY, USA on April 30, 2024. (Photo by Guerin Charles/ABACA Press/Rex Features/Shutterstock)

A person smokes marijuana as marijuana enthusiasts mark the informal annual cannabis holiday, 4/20 (four-twenty), corresponding to the numerical figure widely recognized within the cannabis subculture as a symbol for all things related to marijuana, in Hyde Park in London, Britain on April 20, 2023. (Photo by Maja Smiejkowska/Reuters)