Major Bodies of Water in Ontario: Great Lakes, Rivers, and Inland Seas

Great Lakes (4 of 5 border Ontario)

• Lake Superior (NW border) – largest, deepest, coldest.
• Lake Huron (W border) – includes Georgian Bay, North Channel.
• Lake Erie (S border) – shallowest, warmest, most productive fishery.
• Lake Ontario (S border) – smallest, deepest outlet to St. Lawrence.

Collectively: world's largest freshwater system by area (244,000 km²).

Major Rivers

• Niagara River: Erie→Ontario; Niagara Falls.
• St. Lawrence River: Ontario→Atlantic; Seaway shipping; Lake St. Francis, Lake St. Lawrence.
• Ottawa River: Ontario/Quebec border; hydro, transport, recreation.

Large Inland Lakes

• Georgian Bay (Lake Huron) – "Sixth Great Lake"; 30,000 islands (Thirty Thousand Islands).
• Lake Simcoe (north of Toronto) – ice fishing, boating, cottage country.
• Lake of the Woods (NW, border MB/MN) – 14,000+ islands; walleye/muskie fishery.
• Lake Nipissing (NE) – shallow, productive, historic fur trade route.
• Rainy Lake (border MN) – Voyageurs NP connection.

Significance

Ontario = "Land of Shining Waters" (Iroquoian). 250,000+ lakes = 1/5 world's freshwater. Economic, ecological, recreational backbone.