More than 400 people stripped off and ran into freezing waters to celebrate the autumn equinox – and raise money for charity at Druridge Bay, Britain, September 25, 2016. It was the largest turnout the North East Skinny Dip has ever seen in its five-year history, and it was also the first time it has ever rained on the morning of the event. Revellers gathered from 5.30am on Sunday at Druridge Bay, in Northumberland, before baring all in the North Sea. (Photo by David Charlton Photography)

A plane drops water to put out the fire broke out yesterday in a grassy area in Kizilcahamam district of Ankara and spread to a forest area in Gerede district of Bolu as firefighters, Turkish General Directorate of Forestry teams and officers continue their extinguishing and cooling efforts in the forest fire that is under control on August 22, 2024 in Bolu, Turkiye. (Photo by Emin Sansar/Anadolu via Getty Images)

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)

A milkman crosses through floodwater at Chak Ali Sher village in Wazirabad district on August 28, 2025, after government issued a flood alert for riverside areas of Punjab province. Water has gushed into the eastern province, Pakistan's breadbasket and home to about half of its 255 million people, with three transboundary rivers swelling beyond their banks. The latest monsoon downpour has killed at least 13 people, according to the National Disaster Management Authority. (Photo by Aamir Qureshi/AFP Photo)

A young Ukrainian woman wears an ear of grain braid during a traditional Ukrainian celebration of Kupalo Night, in Warsaw, Poland, on Saturday, June 22, 2024. Ukrainians in Warsaw jumped over a bonfire and floated braids to honor the vital powers of water and fire on the Vistula River bank Saturday night, as they celebrated their solstice tradition of Ivan Kupalo Night away from war-torn home. (Photo by Czarek Sokolowski/AP Photo)

A South Korean woman looks out at the flood water after a torrential rain storm hit the capital city on July 27, 2011 in Seoul, South Korea. South Korea issued a national crisis warning on as torrential rain caused flooding in parts of the country, killing over 35 with at least ten missing. (Photo by Chung Sung-Jun/Getty Images)

Lake Baikal is the world's oldest lake, at 25 million years (possibly older), and deepest, averaging 744.4 metres (2,442 ft).

Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water.