It divides Île J?us (the city of Laval) from the North Shore, the northern mainland suburbs of Montreal (such municipalities as Deux-Montagnes, Saint-Eustache, Boisbriand, Rosem?e, Sainte-Th??e, and Terrebonne.)
The river rises at the narrowing of the Lac des Deux-Montagnes and flows west to east. It joins the Rivi?e des Prairies at the eastern tip of Île J?us, which shortly thereafter rejoins the Saint Lawrence at the eastern tip of the Island of Montreal.
As its name suggests, the river contains a great many small islands.
Not to be confused with the Thousand Islands in the Saint Lawrence River in southeastern Ontario.