The Boundary Creek to Cache Bar river run in Idaho is a challenging and scenic 82-mile stretch of the Middle Fork of the Salmon River. The river offers an exhilarating Class III-IV+ experience, with technical rapids including Velvet Falls, Powerhouse, and Pistol Creek. The best time to float this section of water is typically between June and September, with recommended cfs levels ranging from 1,200-4,000. Be prepared for steep drops, boulder gardens, and tight channels, and plan to spend 5-7 days on the river with a professional guide.