Flowing out of the Helena National Forest in the heart of Montana is the 60-mile Smith River. Like most other waterways in the state, it fluctuates with the seasons, ranging from a trickle in September to a raging torrent in June (thanks to the melting mountain snowpack). Although the river is popular for numerous activities, including camping on its banks, fishing, and swimming, the most prevalent activity on the Smith is floating. Motorized watercraft are not allowed. One of the best put-in spots is in White Sulphur Springs, about 2½ hours south of Great Falls. The best take-out spot is at Eden Bridge State Fishing Access, about 20 miles south of Great Falls. Floating is so popular, in fact, that Montana Fish, Wildlife & Parks limits the number of groups boating down the river and has a lottery system for floating permits. (It also prohibits dogs.) Most trips take four days. Despite the river's popularity, this is still Montana, and the sense of serene isolation that comes from the sight of towering mountains and open prairie will far outweigh any annoyance at seeing a few other boats during your journey.