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 publican serves a glass of stout to a donkey in the East End of London, 1960s. (Photo by Steve Lewis/Getty Images)

A Rohingya refugee girl named Rufia Begum, aged 9, poses for a photograph as she wears thanaka paste at Balukhali camp in Cox's Bazaar, Bangladesh, March 31, 2018. (Photo by Clodagh Kilcoyne/Reuters)

The sunrise over the beach huts at Hamworthy Park in Poole, Dorset, United Kingdom on April 28, 2022. (Photo by Rachel Baker/Bournemouth News)

17-year-old dance student Amelia Hubbard of Halesowen, West Midlands, takes to the park in south Birmingham, United Kingdom on April 14, 2022 to do some spring moves, as temperatures soar in the UK on Good Friday.(Photo by Peter Lopeman/Alamy Live News)

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)

The DFDS King of seaways enters the Mouth of the Tyne on the North East coast in Rough sea on Wednesday, January 18, 2023. (Photo by Owen Humphreys/PA Images via Getty Images)

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