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 dressed as characters from the computer game “World of Warcraft” walk across a field near the town of Kamyk nad Vltavou, Czech Republic, April 28, 2018. (Photo by David W. Cerny/Reuters)

In this photograph taken on July 7, 2018, an Indian Buddhist monk plays with the wind amongst prayer flags on a hill overlooking Tnagyud Gompa monastery in Komik in Spiti Valley in the northern state of Himachal Pradesh. (Photo by Xavier Galiana/AFP Photo)

Taylor Swift attends the 2018 American Music Awards at Microsoft Theater on October 9, 2018 in Los Angeles, California. (Photo by Jon Kopaloff/FilmMagic)

Hindu women worship the Sun god in the polluted waters of the river Yamuna during the Hindu religious festival of Chatth Puja in New Delhi, India, November 3, 2019. (Photo by Adnan Abidi/Reuters)

Convention goers dressed as bright colored Wookiees, a fictional species from the US epic space opera franchise Star Wars, prepare for a group photo outside the Comic Con 2016 in San Diego, California, USA, 22 July 2016. The San Diego Comic Con 2016 runs from 21 until 24 July. (Photo by David Maung/EPA)

A kid from Sichuan provice smokes at an assistance center February 23, 2005 in Shenzhen, Guangdong Province, China. The kids, ranging in age from 7 to 16, are temporary residents of the center, one of the institutions established by China's departments of civil affairs to help and administer beggars, vagrants and juvenile delinquents, after rescission of China's compulsory detainment and relocation system. (Photo by Cancan Chu/Getty Images)

Bella Hadid and Gigi Hadid prepares backstage for Savage X Fenty Show Presented By Amazon Prime Video – Backstage at Barclays Center on September 10, 2019 in Brooklyn, New York. (Photo by Ilya S. Savenok/Getty Images for Savage X Fenty Show Presented by Amazon Prime Video)