II.

Description

The St. Lawrence River begins at the outlet of Lake Ontario and flows to the northeast. In its upper course, which includes the scenic Thousand Islands, the river forms the boundary between the province of Ontario and the state of New York. The river then widens into Lake Saint Francis, which serves for a short distance as the border between the provinces of Ontario and Québec, before flowing wholly in Québec for the remainder of its course. At Montréal the river expands to create Lake St.-Louis, and below Sorel it forms the much larger Lac Saint-Pierre. Below Québec the St. Lawrence broadens from a width of 3 km (2 mi) to 145 km (90 mi) at its mouth.

Ocean tides extend up the river for 800 km (500 mi) to the city of Trois-Rivières. The main tributaries of the St. Lawrence are the Ottawa, Saint-Maurice, and Saguenay rivers from the north, and the Richelieu, Saint-François, and Chaudière rivers from the south. The river is home to a great variety of fish, including sturgeon, smelt, and herring. Belugas (white whales) live near the Gulf of St. Lawrence.