List of Deepest Lakes in the World

Lake Baikal, in southern Siberia, is the deepest lake on Earth. Its floor lies 1,642 metres below the surface — deeper than most of the Mediterranean Sea. Baikal is also the oldest lake in the world, estimated to be 25 to 30 million years old, and its deep, cold, oxygenated waters have produced an evolutionary laboratory comparable only to the Galápagos. Roughly 80 percent of its species are found nowhere else, including the nerpa, the only freshwater seal on the planet. Most of the world's deepest lakes share a common origin: they sit inside tectonic rift valleys, where the Earth's crust has pulled apart, leaving long, narrow, extraordinarily deep basins. Baikal lies in the Baikal Rift Zone. Tanganyika, Malawi, and a handful of others sit inside the East African Rift. Crater Lake in Oregon is the great exception — it is a volcanic caldera, formed about 7,700 years ago when Mount Mazama erupted and collapsed inward. Depth matters for more than just superlatives. Deep lakes store enormous quantities of heat and carbon, stratify seasonally into distinct water layers, and are unusually resistant to pollution because their surface waters mix slowly with the depths. The disadvantage is that once contamination reaches the deep layers, it can persist for centuries. The deepest lake rankings also include two saline water bodies whose lake-versus-sea status is debated — the Caspian Sea at 1,025 metres, and several inland seas that geologists classify as lakes. In this list, we include the Caspian as widely recognised, and otherwise focus on freshwater bodies.