The Saint Lawrence River

The St. Lawrence is the only outflow to the sea from the Great Lakes. For about 115 miles after leaving the lake, the St. Lawrence forms the boundary between the U.S and Canada, making it the second longest river in Canada and 700 miles long.

The Saint Lawrence Seaway includes the Great Lakes, which make up about half of the total length. It is very important economically, its system of canals, locks, deepened channels and waterways are the most important in North America, large sea-going ships can reach Quebec and Montreal, and the seaway allows smaller ships to call at inland lake ports such as Toronto, Hamilton, Buffalo, Detroit, Chicago, Milwaukee and Duluth Superior on the Great Lakes.

On its way to the Atlantic Ocean from Lake Ontario, the Saint Lawrence falls 75 metres. Nearly all of this drop is made in the short and fairly short stretch before the river reaches Montreal 168 miles downstream. Therefore, the water flows extremely fast in this stretch. To avoid th...