Which sea is the largest lake by surface area?

The Caspian Sea is the largest lake by surface area.

Despite its name, the Caspian is a landlocked body of water with no natural outlet to the world’s oceans. It covers roughly 371,000 square kilometres, although its area changes with water levels. Five countries border it: Kazakhstan, Russia, Turkmenistan, Iran, and Azerbaijan.

The Caspian contains saltwater and has a complex geological history. It is a remnant of the ancient Paratethys Sea and is home to distinctive wildlife, including several sturgeon species whose eggs produce caviar. The northern part is shallow, while the southern basin is much deeper.

The Caspian is often compared with Lake Superior, the largest freshwater lake by surface area, and Lake Baikal, the deepest lake. Its title depends on treating it as a lake geographically, despite its traditional maritime name and sea-like size.