Rondeau Provincial Park is the second oldest provincial park in Ontario, Canada, having been established with an order in council on 8 September 1894. The park is located in Southwestern Ontario, on an 8 km long crescentic sand spit extending into Lake Erie. Rondeau is home to the largest area of Carolinian forest in Canada, a long sand beach, a large marsh, approximately half of Rondeau Bay, campgrounds and a cottage community. The name of the park comes from the French words "ronde eau" or "round water" which describes the shape of the harbour sheltered by the peninsula.

Southwestern Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario. It occupies most of the Ontario Peninsula bounded by 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 2,796,367 in 2021.