Below McCoy Chute the Ottawa River divides into two very distinct channels - the Main and Middle. WT named them more than a quarter century ago.  The logic was simple.  The Main Channel had the heaviest flows and the Middle Channel was in the middle of the all the islands in this section of river.  The MAIN is characterized by towering waves and big hydraulics. It provides a "rock-em, sock-em" rollercoaster type of ride in the waves. The hydraulics are like hitting a big wet wall of water that wants to stop the raft. The challenge is to hit it straight and power through. The Main Channel boasts several giants with cute names like Bus Eater and The White Faced Monster.  They don’t look so cute when you are about to drop in. On a river, HYDRAULIC means hole. It is formed when the river pours over a big rock or ledge and creates a hole on the downstream side. Since water seeks its own level, the river takes water from downstream and brings it upstream creating a wall of water rushing upstream to meet the raft sort of like the immovable object versus the irresistible force.

The Main Channel is filled with great rapids:
Lorne, Push Button, Butcher Knife, Lunch Stop Waves, Normans, Coliseum, Dog Leg and Blacks. The Main and Middle join back together at Hells Half Mile.