Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

Georgian men take a break from selling fruit and vegetable at a street market in Tbilisi, Georgia, Wednesday, July 20, 2016. (Photo by Shakh Aivazov/AP Photo)

A dancer sanitizes the pole before performing on the outside patio at Cheerleaders Gentlemen's Club in Gloucester City, New Jersey, U.S. July 17, 2020. (Photo by Rachel Wisniewski/Reuters)

Cadets from the National Cadet Corps (NCC) celebrate after being awarded the first position in the best marching trophy competition during the Republic Day celebrations in the northern Indian city of Chandigarh January 26, 2015. (Photo by Ajay Verma/Reuters)

In this photo released by the Alaska National Guard, Alaska Army National Guard soldiers use a CH-47 Chinook helicopter to removed an abandoned bus, popularized by the book and movie “Into the Wild”, out of its location in the Alaska backcountry Thursday, June 18, 2020, as part of a training mission. Alaska Natural Resources Commissioner Corri Feige, in a release, said the bus will be kept in a secure location while her department weighs various options for what to do with it. (Photo by Sgt. Seth LaCount/Alaska National Guard via AP Photo)

The finishing touches are made to a giant sculpture on the Hayward Gallery entitled “Urban Fox” and made from straw bales on April 18, 2011 in London, England. The sculpture features in the Southbank Centre's 60th anniversary celebration of the 1951 Festival of Britain. The celebration will feature various cultural and creative events and runs from April 22 until September 4, 2011 at London's Southbank Centre. (Photo by Oli Scarff/Getty Images)

Andy Saturn dressed in a space outfit walks in through a subway station over memorial day weekend on May 29, 2021 in New York City. On May 19, 2021 all pandemic restrictions, including mask mandates, social distancing guidelines, venue capacities and restaurant curfews were lifted by New York Governor Andrew Cuomo. (Photo by Alexi Rosenfeld/Getty Images)

Portugal's Patricia Mamona competes in the women's triple jump final during the Tokyo 2020 Olympic Games at the Olympic Stadium in Tokyo on August 1, 2021. (Photo by Dylan Martinez/Reuters)