Amundsen-Scott South Pole Station experiences months of darkness. The sun dips below the horizon on March 21, after which follows several weeks of twilight before complete darkness results. Photo taken on June 25, 2009. (National Science Foundation/Jeremy Johnson)

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.

McKensi Pascall is painted by artist Tom Sebazco at Human Connection Arts 8th Annual NYC Body Painting Day in Union Square Park on Sunday, July 25, 2021 in New York. (Photo by Brittainy Newman/AP Photo)

A protester wearing improvised protective headgear walks away from a cloud of tear gas on July 18, 2021 in Bangkok, Thailand. Student protesters called for a demonstration demanding the resignation of Thailand Prime Minister Prayuth Chan-o-Cha, despite a ban on gatherings because of the country's current Covid-19 outbreak, and folded a demand for better action in combating the virus into their demands. (Photo by Sirachai Arunrugstichai/Getty Images)

A child prays in front of the cenotaph dedicated to the victims of the atomic bombing at the Hiroshima Peace Memorial Park in Hiroshima, western Japan Friday, August 6, 2021. Hiroshima on Friday marked the 76th anniversary of the world's first atomic bombing of the city. (Photo by Kyodo News via AP Photo)

The Radio City Rockettes perform during a rehearsal for their Christmas show in New York City, on October 13, 2021. The 2021 production will run from November 5, 2021, to January 2, 2022, at Radio City Music Hall. (Photo by Timothy A. Clary/AFP Photo)

Elementary school sumo wrestler Kyuta Kumagai competes in a sumo ring at a regional tournament of Junior Olympic Cup All-Japan Elementary School Sumo Championship in Kawasaki, south of Tokyo, Japan, October 17, 2021. (Photo by Kim Kyung-Hoon/Reuters)