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 seven week old Daschund cross puppy waits to be re-homed at the Cheshire Dogs Home on January 4, 2010 in Warrington, England. (Photo by Christopher Furlong/Getty Images)

A male red deer with antlers covered in bracken, walks through undergrowth in Richmond Park in south west London, October 3, 2014. Over 600 red and fallow deer roam in the largest of London's Royal Parks, and have their numbers managed in an annual cull each November and February. (Photo by Toby Melville/Reuters)

The New World porcupine, family Erethizontidae, 1280 Gram born at 11 April 2015 Inventory in Zoo. Counting trade Fairs Weighing the Zoo is at 7 May 2015 too the 108 Birthday Zoo Hagenbeck Hamburg, Germany. (Photo by Imago/ZUMA Wire)

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)

Monkeys sit along a street during a snowfall in Ayubia, some 75 km north of Islamabad, Pakistan on January 7, 2020. (Photo by Aamir Qureshi/AFP Photo)

Migrant children run away from clashes with Mexican National Guards after their group crossed the Suchiate River on foot from Guatemala to Mexico, on the riverbank near Ciudad Hidalgo, Mexico, Monday, January 20, 2020. More than a thousand Central American migrants hoping to reach the United States marooned in Guatemala are walking en masse across a river leading to Mexico in an attempt to convince authorities there to allow them passage through the country. (Photo by Santiago Billy/AP Photo)