The lake is located in east-central Fort Smith region, Northwest Territories, Canada, near the Alberta border. It was named for the Slave Indians. The lake was visited in 1771 by the English explorer Samuel Hearne; it was not completely surveyed, however, until the early 1920s. Fed by several rivers, of which the Slave is most important, and drained by the Mackenzie into the Arctic Ocean, the lake, with an area of 11,030 square miles (28,568 square km), is the fifth largest in North America.