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)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)

An array of colours dwarf visitors to the Rainbow Mountains in the Andes Cordillera in Peru in January 2023, which owes its colours to the minerals contained in the soil. The sulfur offers the yellow colour, iron oxide gives the red and copper sulfate is green. In total, it is made up of 14 different minerals. It was probably caused by weather and volcanic activity. (Photo by Guillaume Astruc/Naturagency/Solent News & Photo Agenc)

A common gallinule runs across the water to escape a nearby alligator at Green Cay Nature Center in Boynton Beach, Florida on September 4, 2025. Unlike most waterbirds, gallinules have long toes that allow them to walk on floating vegetation. The species is known for its loud, cackling calls that often echo through wetlands. (Photo by Ronen Tivony/NurPhoto/Rex Features/Shutterstock)

Sisters Martha Syrett, 6, left, and Etta Syrett, 4, right, measure one of Ian Paton's huge pumpkins at Pinetops Nurseries, Lymington, Hants, UK on October 5, 2025. An enormous pumpkin grown by a pair of green-fingered twins has smashed two world records – it is the heaviest and the longest pumpkin on the planet. Ian and Stuart Paton grew the pumpkin which weighed in at 2,819.8 pounds (1,278.8 kg) – the equivalent of about two bulls. (Photo by Ollie Thompson/Solent News & Photo Agency)

Daniela Burza, 45, wears a Nasty Woman t-shirt and a mask of U.S. Democratic presidential nominee Hillary Clinton as she competes during the Haunted Heats Halloween Surf Contest in Santa Monica, California, U.S., October 29, 2016. (Photo by Lucy Nicholson/Reuters)

A U.S. Army crew chief flying on board a CH-47F Chinook helicopter observes the successful test of flares during a training flight in Afghanistan, March 14, 2018. (Photo by Tech. Sgt. Gregory Brook/Reuters/U.S. Air Force)

U.S. Democratic presidential candidate Hillary Clinton takes a photo with supporters John Nelson, 32, (L) and Dan Stifler, 32, (C) after speaking at the UFCW Union Local 324 in Buena Park, California, U.S. May 25, 2016. (Photo by Lucy Nicholson/Reuters)