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)

Italy's Mount Etna, Europe's tallest and most active volcano, spews lava as it erupts on the southern island of Sicily, Italy, February 28, 2017. (Photo by Antonio Parrinello/Reuters)

Russian Orthodox believers take a dip in the ice cold water of a pond during the celebrations of the Orthodox Epiphany holiday, in Moscow, Russia on January 18, 2024. People believe that dipping into blessed waters during the holiday of Epiphany strengthens their spirit and body. (Photo by Yuri Kochetkov/EPA/EFE)

A four-legged robot dog called SPOT patrols a park as it undergoes testing to be deployed as a safe distancing ambassador, following the coronavirus disease (COVID-19) outbreak, in Singapore on May 8, 2020. (Photo by Edgar Su/Reuters)

Visitors were able to pick their own flowers on this sunflower trail at Gloagburn Farm near Perth, in Scotland on September 13, 2021. Crawford Niven, a farmer, said he was inspired to make the trail, which is made up of nearly 200,000 plants, after seeing similar ones in America and Australia. (Photo by South West News Service)

Studio artist Emma Meehan touches up a new waxwork figure of U.S. drag queen RuPaul which at 7.1feet (2.175 metres) is the tallest human wax figure to be displayed at Madame Tussauds in Blackpool, Britain on April 11, 2022. (Photo by Phil Noble/Reuters)

A ballet dancer practices in the sunshine at the Southbank skatepark in London on Monday, September 17, 2018, as Storm Helene is due to bring unseasonably warm weather in London and the south east, as the low pressure draws up warm air from the south. Forecasters have downgraded warnings that Helene could pose a risk to life when it hits this week – but warned coastal communities to stay vigilant. (Photo by Kirsty O'Connor/PA Wire)