The Lachine Rapids contain large standing waves because the water volume and current do not change with respect to the permanent features in the riverbed, namely its shelf-like drops.
The Lachine Rapids are now passed by the South Shore Canal (Saint-Lambert and Côte Sainte-Catherine locks) of the Saint Lawrence Seaway.
[1] The first European to see the rapids was Jacques Cartier, who sailed up the St. Lawrence River in 1535, believing he had found the Northwest Passage.
Louis Jolliet's July 1674 canoe accident in the rapids destroyed his official report on the existence of the Mississippi River, and raised the standing of his fellow explorer Jacques Marquette.
[4] The first person to design a ship capable of shooting the Lachine Rapids was shipbuilder and carpenter John McQuaid, a native of County Armagh, Ireland who later settled in Kingston, Ontario with his family.