What Is the Depth of the World's Deepest Lake?

A lake forms when water gathers in a low-lying area, either from groundwater surfacing or runoff from rivers and streams filling a depression where water accumulates faster than it can drain. While many lakes are natural, some, like reservoirs, are human-made, created by dams that hold water in place.

While the majority of Earth's lakes contain freshwater, exceptions like Utah's Great Salt Lake exist, which is even saltier than the ocean. Lakes vary greatly in depth; for example, Louisiana's Lake Pontchartrain is quite shallow, with a maximum depth of just 15 feet (4.6 meters). In contrast, Siberia's Lake Baikal plunges to depths exceeding a mile. Here, we explore the world's deepest lake and its eight closest competitors:

1. Lake Baikal, Siberia

Located in southern Siberia within the most seismically active continental rift on Earth, Lake Baikal is a natural lake of extraordinary significance. It is not only the deepest lake globally, measuring 5,387 feet (1,642 meters), but also the oldest and the largest by water volume.

At approximately 25 million years old and comparable in size to Belgium, Lake Baikal is a UNESCO World Heritage Site. This distinction stems from its holding 20 percent of the planet's unfrozen freshwater and hosting around 3,700 unique species of flora and fauna, 80 percent of which are endemic. Among these is the nerpa (Pusa sibirica), the world's sole freshwater seal, found exclusively in Lake Baikal.

2. Lake Tanganyika, Africa

Nestled in the Great Rift Valley of central Africa, Lake Tanganyika borders Zambia, Burundi, Tanzania, and the Democratic Republic of the Congo. As the second deepest lake in the world, it reaches a depth of 4,710 feet (1,470 meters). Its ancient origins have allowed its 2,000+ species of flora and fauna to evolve uniquely, with more than half being endemic. This includes a diverse array of tropical fish found nowhere else on Earth.

More than a million people reside near Lake Tanganyika, relying heavily on its fish for protein. However, since the 1950s, commercial fishing practices have significantly reduced the lake's fish population, threatening its delicate ecosystem.

3. Caspian Sea, Europe/Asia

As the largest inland body of water globally, the Caspian Sea reaches a depth of 3,360 feet (1,025 meters), making it the third deepest lake on Earth. However, its northern Caspian Shelf is notably shallow, averaging only 16 to 20 feet (5 to 6 meters) in depth.

The Caspian Sea's saltwater composition and high salinity are due to its lack of an outlet. Over 5.5 million years, minerals entering the basin have remained trapped, contributing to its briny waters.

Bordered by Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan, the Caspian Sea receives 80 percent of its water from the Volga River. It is also rich in oil and gas, with numerous fossil fuel platforms dotting its landscape.

4. Lake Vostok, Antarctica

Lake Vostok in Antarctica, the fourth deepest lake globally at 2,950 feet (900 meters), stands out as it lies buried beneath 2.2 miles ( kilometers) of ice. Discovered in 1996 via radar technology, this subglacial lake remains in a perpetual state of ice and snow yet contains liquid water.

Fed by meltwater from Antarctica's glaciers, Lake Vostok has no outlet. Despite being devoid of sunlight, it hosts a variety of life forms, primarily bacteria and archaea.

5. O'Higgins/San Martín Lake, South America

Nestled in the remote Patagonian Andes, straddling the Chile-Argentina border, the fifth deepest lake in the world is known as Lago O'Higgins in Chile and San Martín Lake in Argentina. Fed by the O'Higgins and Chico Glaciers, this 2,742-foot-deep (836-meter-deep) lake features an octopus-like shape with eight arms and boasts stunning turquoise waters, tinted milky by glacial rock flour.

6. Lake Nyasa, Africa

Situated on the borders of Mozambique, Tanzania, and Malawi, Lake Nyasa ranks as the sixth deepest lake globally, reaching 2,316 feet (706 meters). Its unique characteristic is that its water layers remain unmixed. The lake boasts extraordinary biodiversity, housing 15 percent of the world's freshwater fish species. Many of these species are confined to specific areas due to their dependence on particular temperature, chemical, and oxygen conditions.

7. Lake Ysyk, Asia

Nestled in the mountains of northeastern Kyrgyzstan, Lake Ysyk is one of the largest high-altitude lakes globally and the seventh deepest at 2,192 feet (668 meters). Locally known as Ysyk-köl, or "Hot Lake," it never freezes, even in winter temperatures as low as minus 15 degrees F (minus 26 degrees C). This is due to its high salinity, which makes it unsuitable for drinking or irrigation but reportedly safe for livestock.

Lake Ysyk, estimated to be around 25 million years old, has a rich human history despite its isolated setting. It served as a key stop along the Silk Road during medieval times, and today, the remains of ancient settlements are visible beneath its waters at the northeastern edge.

8. Great Slave Lake, Canada

Great Slave Lake, the deepest lake in North America at 2,015 feet (614 meters), is located in Canada's Northwest Territories near Alberta. The lake derives its name from the Indigenous people who were enslaved by fur trappers in the surrounding villages during the mid-18th century.

The region around Great Slave Lake is thinly populated due to its extreme climate. During winter, the lake's ice becomes so thick that a temporary ice road is constructed, allowing vehicles to traverse the lake as a shortcut between settlements.

9. Crater Lake, U.S.

Crater Lake, the deepest lake in the United States at 1,943 feet (592 meters), is unique on this list as it was formed by a volcanic eruption. Situated in southern Oregon, this nearly circular lake was created 7,700 years ago when Mount Mazama erupted, causing its summit to collapse and form a caldera, a depression at the top of a volcano.

Crater Lake has no inlets or outlets, making its waters exceptionally clear and blue, as it is solely replenished by rainwater. The only water loss occurs through evaporation.