Algonquin Provincial Park is a provincial park located between Georgian Bay and the Ottawa River in Central Ontario, Canada, mostly within the Unorganized South Part of Nipissing District. Established in 1893, it is the oldest provincial park in Canada. Additions since its creation have increased the park to its current size of about 7653 square kilometres. For comparison purposes, this is about one and a half times the size of Prince Edward Island or the US state of Delaware and about a quarter the size of Belgium. The park is contiguous with a number of smaller, administratively separate provincial parks that protect important rivers in the area, resulting in a total protected area somewhat larger yet.

Its size, combined with its proximity to the major urban centres of Toronto and Ottawa, makes Algonquin one of the most popular provincial parks in the province and the entire country. Highway 60 runs through the south of the park, while the Trans-Canada Highway bypasses it to the north.

Over 2,400 lakes and 1,200 kilometres of streams and rivers are located within the park. Some notable examples include Canoe Lake and the Petawawa, Nipissing, Amable du Fond, Madawaska, and Tim rivers. These were formed by the retreat of the glaciers during the last ice age.