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)

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)

A Bull Frog hops around as Carlos Costly #13 of Honduras brings the ball up against the USA at Sun Life Stadium on October 8, 2011 in Miami Gardens, Florida. (Photo by Marc Serota/Getty Images)

A customer asks for the price of a bittergourd at Duri market on a railway track in Jakarta, January 8, 2016. Indonesia's annual inflation rate cooled to the lowest in six years in December, which might pave the way for the central bank to cut a benchmark rate held at 7.50 percent since February 2015. (Photo by Reuters/Beawiharta)

A man wearing a protective mask poses for a picture with a giant Jade Rabbit installation ahead of celebrations for the Mid-Autumn Festival, amid the coronavirus disease (COVID-19) outbreak in Kuala Lumpur, Malaysia on September 18, 2020. (Photo by Lim Huey Teng/Reuters)

Activists from the climate action group Ocean Rebellion perform a stunt outside the Science Museum, in London, United Kingdom on May 19, 2021. (Photo by Hannah McKay/Reuters)

A man wearing a Spiderman costume jumps across Shibuya crossing in Tokyo on June 8, 2020. (Photo by Charly Triballeau/AFP Photo)