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 man arrested for protesting over human rights abuses makes a court appearance in leg irons at the magistrates courts in Harare, Monday, September 14, 2020. Human rights defenders say it appears the government is using restrictions imposed to combat COVID-19 to suppress political criticism. Opposition officials, human rights groups and some analysts accuse Mnangagwa of abusing the rights of critics, using tactics as harsh as his predecessor, the late Robert Mugabe. (Photo by Tsvangirayi Mukwazhi/AP Photo)

A 69-meter-tall giant Buddha statue stands at the Wat Paknam Phasi Charoen temple on the outskirts of Bangkok on October 12, 2021. (Photo by Jack Taylor/AFP Photo)

The Lake of Lights at Talkin Tarn lake near Brampton in Cumbria, England on October 22, 2017 – where hundreds of lights in the surrounding woodland represent a cherished memory of a relative friend or loved one no longer with us. (Photo by Owen Humphreys/PA Images via Getty Images)

In this picture taken late on June 13, 2017, physiotherapist Masayuki Ozaki takes a bath with his silicone s*x doll Mayu at a love hotel in Yachimata, Chiba prefecture. Around 2,000 of the life- like dolls – which cost around 6,000 USD and come with adjustable fingers, removable head and life- like genitals – are sold each year in Japan, according to industry insiders. (Photo by Behrouz Mehri/AFP Photo)

A woman walks past as South Korean soldiers participate in an anti-chemical and anti-terror exercise as part of the 2023 Ulchi Freedom Shield (UFS) at subway station on August 22, 2023 in Seoul, South Korea. The 11-day exercise, which features drills including the handling of chemical and biological attacks, is a regular joint exercise between U.S. and South Korean troops. (Photo by Chung Sung-Jun/Getty Images)

An Aardvark is weighed by keeper Harry Maskell during a photo-call at ZSL Whipsnade Zoo on August 23, 2022 in Dunstable, England. As part of their regular check-ups, 10,000 animals are having their vital statistics recorded as a way of keeping track of their health and well-being at the UK's largest Zoo. (Photo by Leon Neal/Getty Images)

A diver wearing a Santa Claus costume feeds a sunfish to attract visitors at the Hakkeijima Sea Paradise aquarium in Yokohama, suburban Tokyo on December 17, 2014. Christmas attractions will be held till Christmas Day. (Photo by Yoshikazu Tsuno/AFP Photo)