Identify the source and destination of the St. Lawrence River.?

Answer 1

The source is Lake Ontario.
The destination is the Atlantic Ocean.

Answer 2

The Saint Lawrence River originates at the outflow of Lake Ontario at Kingston, Ontario. From there, it passes Brockville, Cornwall, Montréal, Trois-Rivières, and Québec City before draining into the Gulf of Saint Lawrence, the largest estuary in the world.

It runs 3,058 kilometres (1,900 mi) from the furthest headwater to the mouth (1,197 kilometres or 744 mi from the outflow of Lake Ontario). The furthest headwater is the North River in the Mesabi Range of Minnesota.

Its drainage area, which includes the Great Lakes and hence the world's largest system of fresh water lakes, has a size of 1.03 million square kilometres (390,000 mi²). The average discharge at the mouth is 10,400 cubic metres per second (367,000 ft³/s).

The river includes Lake Saint-Louis south of Montreal, Lac Saint-François at Salaberry-de-Valleyfield and Lac Saint-Pierre east of Montreal. It surrounds such islands as the Thousand Islands near Kingston, the Island of Montreal, Île Jésus (Laval), Île d'Orléans near Québec City, and Anticosti Island north of the Gaspé.

Lake Champlain and the Ottawa, Richelieu, and Saguenay rivers drain into the St. Lawrence.