 The river forms the Lachine Rapids to the west of the island between Lake Saint-Louis and the Bassin de La Prairie, and the between the island and Saint Helen's Island.The Ottawa widens and becomes Lac des Deux-Montagnes north-west of the island.Natural watercourses on either side of Île Perrot, as well as the Sainte-Anne-de-Bellevue Canal on the western tip of the Island of Montréal, connect Lac des Deux-Montagnes and Lake Saint-Louis.