The Box Canyon river run in Idaho offers a challenging Class IV+ whitewater experience with tight, technical rapids, fast currents, and steep drops. The river run is best tackled in late spring or early summer when water levels are at their highest, with a recommended flow of 1,000-2,000 cfs. Obstacles to be aware of include the "Notch" rapid, a narrow chute with a large boulder in the middle, as well as "Pinball," a series of technical rapids with multiple boulders and tight turns. Overall, the Box Canyon river run is recommended for experienced rafters and kayakers looking for a thrilling adventure.