Boise State! Idaho has the most miles of river anywhere in the Lower 48. The Payette has 16 miles of continuous Class V whitewater! From campus, it’s maybe 1 hour to get to some of the best whitewater rafting in the world. If you’re willing to go further for more options, there’s also all the forks of the Salmon, although some of those will require additional permits due to their location in a designated wilderness area (Frank Church River of No Return Wilderness). If you want to take it chill, the Boise runs through campus and can be floated in the summer/fall in an inner tube.