The last mile of the Swan River, from the highway bridge to where it enters Flathead Lake, is known locally as the Wild Mile — a stretch of Class II to III rapids that runs right through the centre of Bigfork. It is a genuinely unusual thing: legitimate whitewater in the middle of an art gallery district.
Kayak rentals are available in town for around $45 for a half-day, and the Wild Mile is manageable for intermediate paddlers in an appropriate kayak. Beginners are better off on the quieter water above the rapids or on Flathead Lake itself. The Swan River Nature Trail follows both the Wild Mile and the slower upper stretch of the river, making for a pleasant walk even if you're not on the water.
The Annual Bigfork Whitewater Festival, held each Memorial Day weekend, features kayak races, a stand-up paddleboard competition, and spectators lining the banks along the entire stretch.