Two massive rock formations rising from the Snake River looked almost unreal, like they had been left behind by a completely different version of Idaho. Launch Beneath The Canyon Walls And Start Paddling UpstreamYour first few strokes immediately put the scale of the Snake River Canyon into perspective. From the launch, the route travels upriver for roughly two miles before reaching the rock formations at Pillar Falls. Perrine Bridge stretches across the Snake River Canyon above Twin Falls, and paddlers heading from Centennial Waterfront Park toward Pillar Falls travel directly beneath it. Rhyolite is volcanic rock, fitting naturally into the broader volcanic history of the Snake River Plain.