Ontario is divided into four regions, including the Canadian Shield, Hudson Bay Lowlands, Great Lakes Lowlands and St. Lawrence Lowlands.
The Canadian Shield covers about two-thirds of Ontario. It's a simple landscape of flat plateaus and low, rounded hills, crisscrossed by rivers and lakes.
There are no mountainous landscapes in Ontario. The average elevation in the Canadian Shield region averages near 305 m (1000 ft). A few elevated areas (high hills and ridges) do reach above 660 m (2165 ft) to the north of Sault Ste. Marie. The same is true northeast of Sudbury where Ontario's highest point stands; Ishpatina Ridge, 693 m (2,274 ft.).
The Canadian Shield slopes gently to the north, where it flattens out into the rocky Hudson Bay Lowlands, land covered by bogs and swampy forests.
The Great Lakes and St. Lawrence lowlands are the narrow southern fringes of the Canadian Shield. The land here is all but a few hundred feet in elevation. In some areas rugged cliffs front the Great Lakes shoreline, Niagara River, Manitoulin Island and others.
Niagara Falls, arguably Canada's most striking landform, straddles the international border between Ontario and the U.S. State of New York. These dramatic falls include the larger Horseshoe Falls at 790 m (2,600 feet) wide, and the smaller American Falls at 320 m (1,060 feet) wide.
Ontario is dissected by hundreds of rivers, many small in length and width. Significant rivers include the Abitibi, Albany, Attawapiskat, Grand, French, Missinaibi, Niagara, Ottawa, Severn and Winisk.
In addition to parts of four of the Great Lakes, Ontario contains thousands of other lakes, many of which are located within the Canadian Shield. Largest include lakes Abitibi, Nipigon, Nipissing, Simcoe, Rainy, Big Trout and Lake of the Woods.