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)

A health worker applies a dose of the AstraZeneca vaccine during the first day of a three-day COVID-19 vaccination campaign for people over age 35 in the Complexo da Maré favela of Rio de Janeiro, Brazil, Brazil, Thursday, July 29, 2021. Some recipients will be monitored to study the rate of protection the vaccines provide and the extent to which virus variants are circulating. (Photo by Bruna Prado/AP Photo)

An aerial view of the Grand Mosque is seen on the second day of Eid al-Adha, during the annual haj pilgrimage in the holy city of Mecca September 25, 2015. (Photo by Ahmad Masood/Reuters)

Russian participants adjust their hair, preparing for the Kremlin Cadet Ball in Moscow, Russia, 08 December 2016. Pupils of cadet schools from different parts in Russia gathered for the first Kremlin Ball, restoring an old tradition of Russian officers and noble girls. (Photo by Sergei Chirikov/EPA)

Members of Germany's elite police unit, the Spezialeinsatzkommando, or SEK, demonstrate an abseil deployment from a helicopter during a media event on March 20, 2012 in Minden, Germany. The SEK is the special response team of Germany's state police force and typically deploys in high-risk situations, such as bank robberies, hostage takings and the arrest of armed and dangerous fugitives. (Photo by Thomas Starke/Getty Images)

Tattooist Jay Freestyle, who is based in Amsterdam, creates what only can be described as works of art that last forever on his clients' skin. His style is freehand – without any sketch or stencil and he inks the incredible drawings straight onto body parts. They might look expertly planned, but the swashes of colour, detailed line work and geometric shapes are all the result of some clever improvisation. Photo: An amazing example of his mixed style. (Photo by Jay Freestyle/360 Media Solutions)

A man dressed as a traditional character in the “Baile de Negras” dance poses for a picture on the feast day of the Virgin of the Candelaria (Candlemas) in the town of Diriomo, some 45 km from Managua, Nicaragua on February 2, 2017 Candlemas falls forty days after Christmas and is celebrated by Catholics as the presentation of Christ at the Temple. (Photo by Inti Ocon/AFP Photo)

Camera trapper Xavier Hubert-Brierre put this large mirror on the side of a road through the jungle in Gabon and left a camera there to record how the animals would respond to their own reflections. A silverback gorilla thought it was seeing another silverback and responded by trying to scare off the potential challenger… (Photo by Xavier Hubert-Brierre/Johns Hopkins University Press)