July 27: Lake Baikal in southern Siberia contains more fresh water than all five North American Great Lakes combined, despite covering a much smaller surface area, highlighting the extraordinary geological features that make it the world’s largest freshwater lake by volume.
According to geological data, Lake Baikal holds approximately 23,000 cubic kilometres of freshwater around 20% of the world’s unfrozen surface freshwater. In comparison, the combined water volume of Lakes Superior, Michigan, Huron, Erie and Ontario is about 22,700 cubic kilometres.
Although the Great Lakes together span nearly 244,000 square kilometres, Lake Baikal covers only about 31,700 square kilometres. Scientists say its immense water storage is the result of its exceptional depth rather than its surface area.
Lake Baikal is the deepest freshwater lake in the world, reaching a maximum depth of about 1,642 metres and an average depth of around 744 metres. Researchers note that even its average depth exceeds the deepest point of any of the Great Lakes, allowing the lake to store an enormous volume of water within a relatively compact basin.
The lake lies within the Baikal Rift Zone, where the Earth’s continental crust is gradually pulling apart. The active rift continues to deepen the basin, while more than 330 rivers and streams feed the lake. Water exits through a single outlet, the Angara River, giving the lake an estimated water residence time of around 330 years.
Scientists estimate that Lake Baikal is about 25 million years old making it the oldest freshwater lake on Earth. Unlike most lakes, which gradually fill with sediment over time, Baikal’s tectonic activity continues to create new space within the basin, helping preserve its immense water volume.
The lake is also recognised as one of the world’s most important freshwater ecosystems. Around 80% of its plant and animal species are found nowhere else, including the Baikal seal (nerpa), the world’s only freshwater seal. Its exceptionally clear waters and unique biodiversity earned it UNESCO World Heritage status in 1996.
Researchers say the comparison between Lake Baikal and the Great Lakes illustrates that a lake’s water storage depends not only on its surface area but also on its depth and geological history. Together Lake Baikal and the Great Lakes contain nearly 40% of the planet’s liquid surface freshwater, underscoring their global importance for freshwater conservation.