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 dog wearing a hat, a pair of sunglass and a lei standing in a fountain of water on August 5, 2022 in Hong Kong, China. The Hong Kong SongKran Festival will be held in a shopping centre from August 5 to 9. (Photo by Vernon Yuen/Rex Features/Shutterstock)

A deer canters past participants in the Darkness into Light event in Killarney, Co Kerry, Ireland on May 7th, 2022. The annual pre-dawn walk raises funds for Pieta, a charity that supports people who are in suicidal distress or engage in self-harm, as well as families affected by suicide. All counselling sessions and other services are provided free of charge. (Photo by James Crombie/INPHO)

A penguin (Manchots Royaux) walks on the basement area, early morning on December 25, 2022, at the Kerguelen Islands, also known as the Desolation Islands, are a group of islands in the sub-Antarctic. (Photo by Patrick Hertzog/AFP Photo)

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)

Monkeys climb onto tourists during the annual Monkey Festival in Lopburi province, Thailand on November 26, 2023. (Photo by Chalinee Thirasupa/Reuters)

Van cats, relatively large, have a chalky white coat, sometimes with ruddy coloration on the head and hindquarters, and have blue or amber eyes or have heterochromia, are seen at “Cat Villa”, established to protect the cats in Van, Turkey on January 20, 2021. Internationally valid “health certificate” is prepared for Van cats, visited by local and foreign tourists, within a project to protect their generations and increasing their numbers. Health certificates with information such as name, breed, gender, eye color, date of birth, tail feature, color, hearing status and identity are given to people who want to adopt cats. (Photo by Mesut Varol/Anadolu Agency 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)