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.

Museum employee Victoria views a giant grouper fish specimen at the Natural History Museum in west London March 25, 2015. It forms part of a new exhibition, “Coral Reefs: Secret Cities of the Sea”, featuring a panoramic virtual dive and over 250 specimens from the Museum's coral, fish and marine invertebrate collection, which opens on March 27. (Photo by Toby Melville/Reuters)

A Hawaiian cleaner wrasse provides its cleaning services to a yellowfin goatfish in a reef community off the Big Island in Hawaii. Cleaner species help rid their hosts of ectoparasites, dead tissue, bacteria and fungi. Studies have shown cleaning to play a vital role in keeping many reef ecosystems healthy. (Photo by Marty Snyderman/Caters News Agency)

American singer-songwriter Miley Cyrus attends the 2020 MTV Video Music Awards, broadcast on Sunday, August 30, 2020 in New York City. (Photo by Vijat Mohindra/MTV VMAs 2020/Vijat Mohindra/MTV VMAs 2020 via Getty Images)

Car headlights illuminate a woman walking through city streets as snow accumulates on December 16, 2020 in Wilkes Barre, Pennsylvania. Winter Storm Gail is expected to bring more than a foot of snow in parts of the Northeast. (Photo by Mark Makela/Getty Images)

Volodymyr, a service member of the Ukrainian armed forces, plays with puppies at fighting positions on the line of separation from pro-Russian rebels in Donetsk region, Ukraine on April 10, 2021. The two unnamed puppies living on frontline positions will be taken home and named by soldiers departing on troops rotation. (Photo by Oleksandr Klymenko/Reuters)

Aerial photo taken on April 20, 2018 shows the view of advection fog above Qingdao, a coastal city in east China' s Shandong Province. (Photo by Lu Hui/Xinhua News Agency/Eyevine)

A roadside vendor selling apples is seen through a plastic sheet that he uses to cover himself from rain, in Srinagar, Indian state of Jammu and Kashmir on November 14, 2018. (Photo by Danish Ismail/Reuters)