The Lachine Rapids are located on the Saint Lawrence River in, of all places, Lasalle. Lasalle is on the southern tip of the Island of Montreal.

The Lachine Rapids contain large standing waves created by a huge water volume, a very strong current and a number of shelf-like drops in the river bed. Seasonal variations in the water flow do not change the position of the waves, although they do change the size and shape of the waves.

In the past these rapids presented a considerable barrier to maritime traffic. Until the construction of the Lachine Canal through Montreal, the rapids had to be portaged or run by intrepid river pilots.

The Lachine Rapids are now bypassed by the Saint Lawrence Seaway.

Whitewater rafting and jet boat expeditions to the rapids are available minutes from downtown Montreal, as is whitewater kayaking and river surfing.