Which lake is Ontario’s largest lake located entirely within the province?

Lake Nipigon is Ontario’s largest lake located entirely within the province.

The lake covers about 4,848 square kilometres and lies north of Lake Superior. Its waters flow through the Nipigon River into Lake Superior, making it part of the Great Lakes drainage system even though it is not one of the five traditionally recognized Great Lakes.

Lake Nipigon is surrounded by boreal forest and exposed Canadian Shield rock. Its shoreline includes many islands, and the region is known for remote landscapes, fishing, canoeing, and winter conditions. The lake’s basin was shaped by glacial processes during the last Ice Age.

A common mix-up is to call Nipigon a Great Lake. It is hydrologically connected to Lake Superior and sometimes appears in broader Great Lakes discussions, but standard geographic lists name only Superior, Michigan, Huron, Erie, and Ontario as the Great Lakes.