How Deep Is the Deepest Lake in the World?

Lake Baikal is a natural lake situated in southern Siberia in the most seismically active continental rift in the world. Not only is Lake Baikal the deepest lake in the world, clocking in at 5,387 feet (1,642 meters) deep, it's also the world's oldest lake, and its largest lake by volume of water. 

Lake Baikal is around 25 million years old and roughly the size of Belgium. This incredible body of water earned the distinction of being a UNESCO World Heritage Site due to the fact that it contains a full 20 percent of the world's unfrozen fresh water and is home to around 3,700 animal and plant species, 80 percent of which live nowhere else in the world. For instance, the nerpa (Pusa sibirica), found only in Lake Baikal, is the only freshwater seal in the world. 

In the Great Rift Valley of central Africa, on the borders shared by Zambia, Burundi, Tanzania and the Democratic Republic of the Congo sits Lake Tanganyika, the second deepest lake in the world. Lake Tanganyika is 4,710 feet (1,470 meters) deep and very old, which means the plants and animals have had time to become specialized to its unique ecosystem. Lake Tanganyika is home to over 2,000 species of flora and fauna, including many tropical fish, and over half of them live nowhere else in the world. 

Over a million people live around Lake Tanganyika, and a lot of the protein consumed by this population comes from fish. However, commercial fishing practices started in the 1950s have depleted the lake's fish population. 

The Caspian Sea is the largest inland body of water in the world, and at 3,360 feet (1,025 meters) deep, it's the third deepest lake on Earth. On its northern end, on what's called the Caspian Shelf, it is actually very shallow, averaging around 16 to 20 feet (5 to 6 meters).

The reason the Caspian Sea is a saltwater lake, and its waters are so briny is because it has no outlet, so any minerals that have found their way into the basin over the past 5.5 million years have become stranded there. 

Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan all share coastlines of the Caspian Sea, and the Volga River provides 80 percent of its water. The Caspian Sea is rich in oil and gas, and fossil fuel platforms are a common sight from its shores.

Antarctica's Lake Vostok is not only the fourth deepest lake in the world at 2,950 feet (900 meters) deep, it is a bit of an outlier in a list of deepest lakes in that it's buried under 2.2 miles (3.5 kilometers) of ice. This subglacial lake was discovered in 1996 using radar technology, and although it's covered in ice and snow year-round, it contains liquid water. 

Lake Vostok has no outlet but is fed by meltwater off Antarctica's glaciers. And although sunlight never reaches it, it seems to have more than a few inhabitants — mostly bacteria and archaea.

In a remote part of the Patagonian Andes, on the border between Chile and Argentina, sits the fifth deepest lake in the world, called Lago O'Higgins by Chileans and San Martín Lake by Argentineans. Fed by the O'Higgins and Chico Glaciers, this 2,742-foot-deep (836-meter-deep) lake is shaped like an octopus with eight arms, and has beautiful turquoise waters, made milky by glacial rock flour.

On the border between Mozambique, Tanzania and Malawi sits Lake Nyasa, the sixth deepest lake in the world. At 2,316 feet (706 meters) deep, Lake Nyasa — also called Lake Malawi — is unique in that its water layers don't mix. The lake has extremely high biodiversity — it's home to a full 15 percent of freshwater fish species on the planet — and many of the species are obligated to stay in certain areas of the lake due to their requirements for temperature, chemical composition and dissolved oxygen. 

In the mountains of northeastern Kyrgyzstan sits Lake Ysyk, one of the largest high-mountain lakes in the world, and the seventh deepest at 2,192 feet (668 meters) deep. The local name for the lake is Ysyk-köl, or "Hot Lake" because it never freezes over, despite winter temperatures regularly plummeting to minus 15 degrees F (minus 26 degrees C). This is because Lake Ysyk's salinity is high — too high to drink or irrigate crops, but reportedly not too salty to refresh livestock. 

Lake Ysyk is probably around 25 million years old, but also shares a lot of history with humans, despite its remote location. It was a stop along the Silk Road in medieval times, and the remnants of ancient settlements can be seen through the waters at the northeast end of the lake.

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

The area around the lake is sparsely populated because the climate is so harsh. The ice on the lake is so thick during winter months that a temporary ice road is set up for cars and trucks to drive over Great Slave Lake as a shortcut between settlements.

Crater Lake is the deepest lake in the United States. At 1,943 feet (592 meters) deep, it's also the only lake on this list formed by the eruption of a volcano. Located in southern Oregon, Crater Lake is a nearly perfect ring of water that formed 7,700 years ago when a giant volcano called Mount Mazama erupted, and the top caved in, forming a caldera, a hole in the top of a mountain that forms after a volcanic eruption. 

Crater Lake has no input or output — the waters are crystal clear and blue because it's fed entirely by rainwater. The only water leaving Crater Lake does so through evaporation.