aka Saute Moutons
This might be the most (summer type) fun that I've ever had! Do not miss this when in Montreal.
First you sit through an info session which is amusing & multi lingual. They offer all kinds of goofy looking but much needed (trust me, and them) clothing and life jackets. You can also leave your valuables with them, and there are changing rooms. They say bring a towel and a change of clothing and they are not kidding, even undergarments, as you'll be soaked through. Pockets in front of you on the boats can hold small valuables, but wrap them in a plastic bag.
Next you board the boats and ride to the Lachine (?) rapids area. Ask the staff where to sit if you want to get really nailed by the waves. People in the front row get constantly hammered with walls of waves. Those in the middle and toward the back get it too, just not so constantly - and that's the fun of it. Who knew that there were class five rapids ten minutes from the city?! The helmeted & bull horned guide explains what's going on. The boats are so well built, powerful (twin 66o motors?!) and the captain so skilled, it's not scary, just crazy fun. The ride back even has a few surprises.