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.

Thousands of revelers continue to enjoy themselves throughout the night on Sunrise Beach on February 25, 2005 in Haadrian, Koh Phangan. (Photo by Shaul Schwarz/Getty Images)

The supermoon rises behind Glastonbury Tor on September 27, 2015 in Glastonbury, England. Tonight's supermoon, so called because it is the closet full moon to the Earth this year, is particularly rare as it coincides with a lunar eclipse, a combination that has not happened since 1982 and won't happen again until 2033. (Photo by Matt Cardy/Getty Images)

A man flies a kite on the Bund while buildings of Pudong's Lujiazui financial district stand across the Huangpu River as the sun rises in Shanghai, China, on Friday, October 2, 2015. (Photo by Qilai Shen/Bloomberg)

Singer Rihanna prepares for a photoshoot with photographer Annie Leibovitz in Havana, Cuba, May 28, 2015. (Photo by Reuters/Stringer)

In this photo taken late Thursday, May 7, 2015, a prison guard, left, and seated inmates cast shadows on a wall while waiting for the beginning of a rock concert by Romanian band Pro Musica, inside the Popa Sapca jail in Timisoara, western Romania. (Photo by Adi Piclisan/AP Photo)

Kim Kardashian is seen on February 15, 2017 in New York City. (Photo by Team GT/GC Images)