There are bodies of water in Ontario.
The Great Lakes ( les Grands-Lacs ) , also called the Laurentian Great Lakes and the Great Lakes of North America , are a series of interconnected freshwater lakes located primarily in the upper mid-east region of North America , on the Canada -- United States border , which connect to the Atlantic Ocean through the Saint Lawrence River . Ontario . Almost all of Ontario 's 2700 km border with the United States follows inland waterways : from the west at Lake of the Woods , eastward along the major rivers and lakes of the Great Lakes/Saint Lawrence River drainage system .