Which is the world’s largest lake (by surface area)?

Concept

"Largest lake by surface area" ranks bodies of water by the total area of their water surface, regardless of whether the water is fresh or salt. A lake is an inland body of water not directly connected to the open ocean; by this definition even a vast saline, ocean-detached basin still counts as a lake.

Application

Compare the approximate surface areas of the four candidates:

The Caspian Sea, at roughly 371,000 sq km, is by far the largest enclosed inland water body on Earth, exceeding the next candidate by more than four times.

Cross-check / Contrast

• Lake Superior is the largest freshwater lake by surface area, but it is only about 82,100 sq km, far short of the Caspian.

• Lake Victoria is Africa's largest lake and the largest tropical lake, yet at ~68,800 sq km it is much smaller.

• Lake Huron is one of the North American Great Lakes (~59,600 sq km), smaller still.

• Despite carrying "Sea" in its name, the Caspian is landlocked and not connected to the open ocean, so it is classified as a lake.

Therefore the world's largest lake by surface area is the Caspian Sea.