Lakes are inland bodies of standing water surrounded by land. They form in natural depressions where water collects and remains. The most common source is glacial activity. When glaciers advance and retreat, they carve out basins that later fill with meltwater. Basins are also created by tectonic movement, volcanic craters, landslides or river blockages.

The scientific definition of a lake is: A body of standing inland water, usually of considerable size, occupying a natural basin, and not part of the ocean.

The primary difference between a lake and a sea is connection to the ocean. Seas are typically large bodies of saltwater that are partially enclosed by land but directly connected to an ocean, such as the Mediterranean Sea or the Caribbean Sea. Lakes, on the other hand, are fully enclosed by land.

The origin of a lake determines its depth, shape, salinity, and longevity. Most lakes are freshwater. However, some lakes form in arid regions through poor drainage, where evaporation exceeds outflow, creating salt lakes. Surface area varies over time due to environmental conditions and seasonal changes. Over time, a lake’s size can change or even disappear entirely.

Below are the ten largest lakes in the world by surface area.

Largest Lakes in the World

World’s Largest Lakes by Surface Area

1. Caspian Sea – 143,200 sq mi (371,000 km²)

The Caspian Sea is the largest enclosed inland water body on Earth. Despite its name, it’s a lake, not a sea, because it is not connected to any ocean. It borders five countries: Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. Its size dwarfs all other lakes, covering more than four times the area of Lake Superior.

The Caspian is salty, but only about a third as saline as ocean water. It formed from an ancient ocean that got cut off and trapped inland. It has no natural outlet, so water loss occurs only through evaporation. The north is shallow and freshwater, while the south is deep and more saline, showing major variation even within the same lake.

2. Lake Superior – 31,700 sq mi (82,100 km²)

Lake Superior is the largest freshwater lake by surface area. It sits between the U.S. and Canada, bordered by Minnesota, Wisconsin, Michigan, and Ontario. The lake was carved out by glaciers during the last Ice Age. It’s part of the Great Lakes system and drains through Lake Huron into the Atlantic.

Lake Superior contains 10% of the world’s surface freshwater. Its average depth is 483 feet (147 meters), but it reaches a maximum depth of 1,333 feet (406 meters). The water is cold year-round, and storms on Superior are notoriously violent, with over 350 shipwrecks recorded. Despite its size, it’s losing water slowly due to climate change-driven evaporation.

3. Lake Victoria – 26,600 sq mi (68,800 km²)

Lake Victoria is Africa’s largest lake by surface area and the largest tropical lake in the world. It sits between Uganda, Tanzania, and Kenya. Unlike most of the world’s largest lakes, Lake Victoria is shallow, averaging only 130 feet (40 meters). It was formed by slow geological uplift and drainage basin shifts, not by glaciers or tectonics.

The lake feeds the White Nile and supports over 30 million people in the region. It’s a biodiversity hotspot, especially known for its hundreds of endemic cichlid fish species. Invasive species like the Nile perch have heavily disrupted the lake’s natural ecosystem. It has experienced major shrinkage in the past due to droughts and human demand.

4. Lake Huron – 23,000 sq mi (59,600 km²)

Lake Huron is the second largest of the Great Lakes and borders Michigan (U.S.) and Ontario (Canada). It’s connected to Lake Michigan via the Straits of Mackinac, making them one hydrological lake by volume.

Lake Huron has the longest shoreline of any of the Great Lakes, including over 30,000 islands. The largest of these, Manitoulin Island, is the world’s biggest island within a lake. It was formed by glacial retreat, like the rest of the Great Lakes. Lake Huron’s average depth is 195 feet (59 meters), with a maximum depth of 750 feet (229 meters). It plays a key role in shipping, recreation, and hydroelectric power. The lake is vulnerable to storms, invasive species, and algal blooms.

5. Lake Michigan – 22,400 sq mi (58,000 km²)

Lake Michigan is the only one of the Great Lakes entirely within the U.S. It touches Illinois, Indiana, Wisconsin, and Michigan. Like its neighbors, it was formed by retreating glaciers that left a deep basin. Chicago and Milwaukee sit on its western shore, making it a major economic hub.

The lake is deep—925 feet (282 meters) at its deepest point—and stores vast volumes of freshwater. Its beaches and dunes are popular with tourists, and winter storms often create ice formations along the shoreline. Lake Michigan also faces heavy pollution and invasive species like zebra mussels. Despite this, it remains vital for commerce and recreation in the Midwest.

6. Lake Tanganyika – 12,700 sq mi (32,900 km²)

Lake Tanganyika is Africa’s second largest lake by surface area but its deepest and oldest. It borders four countries: Tanzania, the Democratic Republic of the Congo, Burundi, and Zambia. It is a rift lake, formed by the tectonic activity of the East African Rift. With a maximum depth of 4,820 feet (1,470 meters), it’s the second-deepest lake in the world after Lake Baikal.

Tanganyika holds about 16% of the world’s freshwater by volume. It has extremely high biodiversity and is home to hundreds of endemic fish species. The lake’s depth and age make it a valuable site for climate and geological research. Local communities rely heavily on it for fishing, transport, and freshwater.

7. Lake Baikal – 12,200 sq mi (31,500 km²)

Lake Baikal is the deepest and oldest freshwater lake in the world. Located in southern Siberia, Russia, it’s around 25 million years old. At 5,387 feet (1,642 meters) deep, Baikal holds more water than all the Great Lakes combined. It formed in an active continental rift zone and is still growing.

The lake is surrounded by mountains and remains frozen for five months of the year. Baikal supports over 2,000 species, most of which are found nowhere else. This includes the Baikal seal, the only freshwater seal species in the world. Its isolated location has helped preserve its clarity and biodiversity, though industrial pollution is a growing threat.

8. Great Bear Lake – 12,100 sq mi (31,300 km²)

Great Bear Lake is the largest lake entirely within Canada. It’s located in the Northwest Territories, just below the Arctic Circle. The lake is glacial in origin and remains frozen nearly half the year. It reaches a maximum depth of 1,463 feet (446 meters).

The surrounding region is sparsely populated and largely undeveloped. This isolation keeps the lake exceptionally clear and unpolluted. It’s rich in trout and whitefish, and First Nations communities have long relied on it for food and transport. Due to its remoteness and pristine condition, it’s a designated Biosphere Reserve by UNESCO.

9. Lake Malawi (Lake Nyasa) – 11,400 sq mi (29,600 km²)

Lake Malawi, also known as Lake Nyasa, is the southernmost lake in the East African Rift system. It borders Malawi, Mozambique, and Tanzania. Like Tanganyika, it is a deep rift lake, reaching depths of over 2,300 feet (701 meters).

The lake is famous for its cichlid fish diversity—over 700 species, most found nowhere else. Lake Malawi’s warm, clear waters are ideal for snorkeling and tourism. The surrounding region is densely populated, and many communities rely on the lake for fishing and irrigation. Tensions have risen in the past over territorial boundaries and oil exploration rights. Despite these pressures, the lake remains ecologically rich and visually stunning.

10. Great Slave Lake – 11,000 sq mi (28,600 km²)

Great Slave Lake is Canada’s second-largest lake and North America’s deepest. It lies in the Northwest Territories and gets its name from the Slavey First Nations people. It reaches depths of 2,015 feet (614 meters), deeper than any U.S. lake. Like other northern lakes, it was carved by glaciers and stays ice-covered for much of the year.

The lake is part of the Mackenzie River system and serves as an important freshwater reservoir. Its southern shore hosts Yellowknife, the capital of the Northwest Territories. The lake is also used for ice roads in winter and floatplanes in summer. Its remote location helps preserve its clean water and natural beauty.