What is the world's largest inland lake?

The world's largest inland lake is the Caspian Sea. Despite its name, the Caspian is an enclosed body of water with no natural outlet to an ocean, so it is classified geographically as the world's largest lake by surface area.

The Caspian is unusual because it is saline and sea-like, yet it is not connected to the global ocean. It lies between Europe and Asia, and its shoreline is shared by Russia, Kazakhstan, Turkmenistan, Iran, and Azerbaijan. The Volga River supplies much of its inflow, while evaporation is its primary water loss.

The Caspian covers roughly 371,000 square kilometres, although its exact area changes with water levels. It contains about 40–44% of the world's lake water by area-based comparisons. A common mix-up is Lake Superior: Superior is the largest freshwater lake by surface area, while the Caspian is larger overall. The Caspian's status also explains why some references call it both a sea and a lake.