The East Fork to Challis Bridge river run in Idaho on the Salmon River is a Class III-IV whitewater rafting trip with challenging rapids and stunning scenery. This section of water is best navigated from mid-June to mid-July with recommended flows of 1,200-2,000 cfs. Obstacles include Big Mallard Rapid and Eightmile Rapid, both of which require technical maneuvering. The river run difficulty increases with higher water levels, making it best suited for experienced paddlers. Overall, this river run offers a thrilling adventure for those seeking a challenging and scenic rafting experience.