An areal view of the lake in the form of a heart in Rodgau, near Frankfurt, Germany, Friday, May 24, 2024. (Photo by Michael Probst/AP Photo)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

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.

Students from CAS Ballet Theatre School stretch on the sidewalk Saturday, February 20, 2016, in Ann Arbor, Mich. (Photo by Junfu Han/The Ann Arbor News via AP Photo)

American actress, model, and singer Ashley Benson arrives at Paris Hilton's wedding party inBeverly Hills, CA. on November 14, 2021. (Photo by Backgrid USA)

American singer-songwriter FLETCHER celebrates with Tequila Don Julio 1942 at her Pride after party in Los Angeles, CA on June 9, 2023. (Photo by Taylor Kahan)