Ontario Lakes & Rivers Map

The Great Lakes

Four of the five Great Lakes form Ontario's southern and western edge, holding about a fifth of the world's surface fresh water between them. They are the defining feature of the province's geography, climate and economy.

Lake	Notes
Lake Superior	The largest freshwater lake in the world by area, and the deepest and coldest of the Great Lakes. Forms Ontario's northwest shore.
Lake Huron	Includes Georgian Bay and Manitoulin Island, the largest freshwater island on Earth. Famous for its beaches and shipwrecks.
Lake Erie	The shallowest and warmest Great Lake, on the south shore by Windsor and the Niagara region. Its warmth drives the Lake Erie snowbelt and the Niagara wine climate.
Lake Ontario	The easternmost and smallest by surface area, but very deep. Toronto, Hamilton and Kingston sit on its shore; it drains to the St. Lawrence.

For the shoreline in detail, see the Great Lakes shoreline map.

Major inland lakes

Beyond the Great Lakes, Ontario contains around 250,000 lakes - more than any other comparable area in the world. The largest lying entirely within the province is Lake Nipigon, north of Lake Superior. Other notable inland lakes include:

• Lake of the Woods — a huge, island-filled lake shared with Manitoba and Minnesota, near Kenora.
• Lake Nipissing — a broad, shallow lake at North Bay, draining to Georgian Bay via the French River.
• Lake Simcoe — the big cottage and ice-fishing lake just north of the GTA.
• Lac Seul and Rainy Lake — large northwestern reservoirs and canoe waters.
• The Muskoka and Kawartha lakes — the heart of cottage country.

Major rivers and waterways

Ontario's rivers split into two great drainage systems. Southern rivers flow toward the Great Lakes and the Atlantic; northern rivers flow the opposite way into Hudson Bay and James Bay.

• Ottawa River — forms the entire boundary with Quebec and flows past the national capital, Ottawa.
• St. Lawrence River — the outlet of the entire Great Lakes system, carrying ocean ships past Kingston and the Thousand Islands.
• Niagara River — links Lake Erie and Lake Ontario and plunges over Niagara Falls.
• Grand River — southern Ontario's largest river, running through Kitchener, Cambridge and Brantford; a Canadian Heritage River.
• Thames River — flows through London to Lake St. Clair.
• Albany, Moose, Severn, Attawapiskat and Winisk rivers — the great northern rivers draining the Shield and Lowlands into the salt water.

Historic canals

Two famous canal routes turn Ontario's lakes and rivers into through-routes for boats:

• Trent-Severn Waterway — a 386 km National Historic Site linking Lake Ontario at Trenton to Georgian Bay at Port Severn through the Kawartha Lakes, complete with the world's highest hydraulic lift lock at Peterborough.
• Rideau Canal — a 202 km UNESCO World Heritage canal joining Ottawa and Kingston, the oldest continuously operated canal in North America.

Watersheds: which way the water flows

A continental drainage divide crosses Ontario. South of it, water flows to the Great Lakes and the St. Lawrence and on to the Atlantic Ocean. North of it - across most of the province by area - water flows into Hudson Bay and James Bay, part of the Arctic watershed. The divide runs through the high ground of the Canadian Shield, which is why a few hours' drive north of Lake Superior can put you in country whose rivers never reach the Great Lakes at all.

Common questions

How many lakes does Ontario have?

Roughly 250,000 - more than any comparable area on Earth. With the Great Lakes, the province holds a large share of the planet's fresh surface water.

What is the largest lake entirely in Ontario?

Lake Nipigon, north of Lake Superior. The Great Lakes are bigger but are shared with the United States.

What are the major rivers in Ontario?

In the south: the Ottawa, St. Lawrence, Niagara, Grand and Thames. In the north: the Albany, Moose, Severn, Attawapiskat and Winisk.

What is the Trent-Severn Waterway?

A 386 km canal route from Lake Ontario at Trenton to Georgian Bay at Port Severn, through the Kawartha Lakes - a National Historic Site and popular boating route.

Related maps

• Ontario geography — landform regions and physical features
• Great Lakes map — the four lakes that border Ontario
• Canadian Shield map — the rock that holds all those lakes
• Muskoka map — cottage-country lakes
• Provincial parks map — canoe-trip waters and waterway parks