The Caspian Sea is the world’s largest lake by surface area, covering about 371,000 square kilometers (143,244 square miles), roughly the size of Japan. It is an endorheic basin with no outflow to the ocean, lying between Europe and Asia and bordered by Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan.
Despite its name, it is classed as a lake because it is landlocked; its water is about 1.2% salt, roughly a third as salty as average seawater. The largest freshwater lake by area is Lake Superior in North America.
Source: Wikipedia, Caspian Sea