Southwestern Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario, centered on the city of London. It occupies most of a peninsula that is bound on three sides by water: Lake Huron, including Georgian Bay, to the north and northwest; the St. Clair River, Lake St. Clair, and Detroit River, to the west; and Lake Erie to the south. To the east, on land, Southwestern Ontario is bounded by Central Ontario and the Golden Horseshoe. The region had a population of 2,504,878 in 2011.