The Beartrap Canyon river run on the Madison River in Montana is a challenging and exciting stretch of water. The river features Class III and IV rapids, with several large boulders and tight channels that require careful maneuvering. The best time to float this section of the river is from June to September, with recommended CFS levels between 1,000 and 3,000. It's important to note that the river can be dangerous at higher levels, and rafters should always wear appropriate safety gear and be experienced in navigating difficult rapids. Overall, the Beartrap Canyon river run offers a thrilling and scenic adventure for experienced rafters.