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.

A bucket of water is splashed on a woman during the Songkran water festival to celebrate the Thai New Year, in Prachinburi Province, Thailand, April 13, 2024. (Photo by Wason Wanichakorn/AP Photo)

A woman wearing a sweet girl cosplay mask strikes a pose during a flower watching or Hanami event, in the Japanese Garden of Bucharest, Romania, April 13, 2024. (Photo by Andreea Alexandru/AP Photo)

A competitor in the carting category of the Henrik Sečnik dog mushing race in Hraše, Slovenia on April 8, 2024. Over 100 dogs and their owners from Slovenia and abroad competed in the 10th edition of this international race. (Photo by Luka Dakskobler/SOPA Images/Rex Features/Shutterstock)

People gather for the second annual “Cat Beauty Festival” organized by Royal Veterinary Hospital in Sulaymaniyah, Iraq on July 2, 2025. Around 200 cats participated in the event, where the first round was determined by social media votes. The winner, a cat named “Gule Rana”, was selected by a jury. The festival aims to promote animal love and raise awareness about feline care. (Photo by Fariq Faraj Mahmood/Anadolu via Getty Images)

A robot using artificial intelligence is displayed at a stand during the International Telecommunication Union (ITU) AI for Good Global Summit in Geneva, on May 30, 2024. Humanity is in a race against time to harness the colossal emerging power of artificial intelligence for the good of all, while averting dire risks, a top UN official said. (Photo by Fabrice Coffrini/AFP Photo)