The Lachine Rapids drop thirteen metres over three kilometres, carving the St. Lawrence into a ribbon of standing waves and hydraulic rollers that claimed hundreds of vessels during the fur trade era. Before the canal system opened in 1825, voyageurs portaged their cargo around this stretch rather than risk the chaos downstream from Lake Saint-Louis. Today those same rapids serve as North America's largest urban whitewater playground, generating Class III and IV features within sight of Montreal's skyline. Jet boat tours Montreal operations launched in the early 1990s, converting what was once a navigation hazard into a controlled adrenaline circuit. Purpose-built vessels carry passengers through standing waves that reach two metres in height during peak spring runoff. The rapids form where the river narrows and accelerates over a limestone shelf, creating hydraulic features that remain navigable year-round but intensify between April and June when snowmelt swells the St. Lawrence to twice its late-summer volume. Operators throttle into these features at angles calibrated to maximize spray while maintaining hull integrity—a forty-five-degree approach to a standing wave generates enough water displacement to drench passengers in the forward rows. The Lachine Canal, which parallels the rapids for fourteen kilometres, was once the economic spine of industrial Montreal. Mills and factories lined its banks, drawing power from controlled flows that bypassed the whitewater entirely. When container shipping rendered the canal obsolete in the 1970s, the waterfront transitioned from industrial corridor to recreational asset. Parks Canada reopened the canal to pleasure craft in 2002, and jet boat operators now share the entry basin at the Old Port with kayakers, cyclists on the adjacent tow path, and sightseeing cruises that avoid the rapids altogether. Modern jet boat hulls are reinforced aluminum with no external propellers—water intake jets provide thrust, allowing operators to navigate shallow rock gardens that would shred conventional drives. Safety briefings emphasize secure seating and the physics of standing waves: when the bow climbs a two-metre wall of water, passengers experience a brief zero-gravity pause before the hull slams into the trough. Guides position vessels to thread narrow channels between submerged boulders, using the current's momentum to slingshot into the next feature. The entire circuit runs twenty to thirty minutes, depending on water levels, covering a route that early fur traders would have spent half a day portaging around on foot.