One of the great rivers of North America; issues in a noble stream from Lake Ontario, and flowing due NE. discharges into the Gulf of St. Lawrence, forming a broad estuary; is 750 m. long and from 1 to 4 m. broad; the scenery in parts is very grand, notably in the expansion—the Lake of the Thousand Isles; is navigable for large steamers as far as Montreal: the Ottawa is its chief tributary; in winter navigation is suspended on account of the ice.