The Lachine Rapids owe their present name to the 19th century British merchants and armed forces, when LaSalle still formed part of the Parish of Lachine. And they owe their strength to a 13-metre difference in level between lac Saint-Louis and bassin de La Prairie.
The most turbulent part of the Rapids is located between the entrance to the aqueduct canal and the limits of LaSalle and Verdun. There, a number of small and bigger islands can be found, including île aux Hérons, île aux Chèvres and île au Diable. This site was converted into a park in 1937 and nearly 225 bird species come here, including a protected one: the Great Blue Heron.