Tourists visit the Corral Canyon Cave in Malibu, Calif., Friday, May, 6, 2016. The cave, better known by the misleading moniker “Jim Morrison Cave” is now closed to the public until further notice. Large crowds have shown up on a daily basis to see the often vandalized cave and in some cases add to the vandalism with graffiti of their own. (Photo by Damian Dovarganes/AP Photo)

In this February 2, 2014 photo, people take pictures inside a cave at Apostle Islands National Lakeshore in northern Wisconsin, which has been transformed into a dazzling display of ice sculptures by the arctic siege gripping the Upper Midwest. (Photo by Brian Peterson/AP Photo/Minneapolis Star Tribune)

People look at a tanker after it fell into a caved-in area on a road in Xi'an, Shaanxi province, July 27, 2013. No casualty was reported in the accident, according to local media. (Photo by Reuters/Stringer)

Phuket, Thailand. The girl is in the pool, which is higher than the land, and the elephant is on the land behind the pool. The photographer used an underwater bag to get a half submerged image. (Photo by Justin Mott)

Visitors are seen with giraffes on a bus at Safari Park in Kanchanaburi Province, Thailand, January 19, 2020. Kanchanaburi in western Thailand an area known for its waterfalls and caves. (Photo by Rachen Sageamsak/Xinhua News Agency/Eyevine)

“After an afternoon of hiking and exploring the caves of Rhossili Bay, West Glamorgan, we caught the sun breaking through the clouds”. (Photo by Megan Warren-Davis/The Guardian)

A cave diver in Anhumas Abyss, Bonito, Brazil. (Photo by Marcio Cabral/Epson International Pano Awards 2018)

Tree trunks and rocks are set up to support a leaning wall of Li Yonghua's damaged cave house in an area where land is sinking next to a coal mine, in Helin village of Xiaoyi, China's Shanxi province, August 2, 2016. (Photo by Jason Lee/Reuters)