The river that forms Glacier National Park's southwestern boundary was protected before most of the outfitters running it existed: the Middle Fork Flathead was designated Wild and Scenic in 1976, one of the earliest such listings in Montana. That designation matters. It froze the corridor in place — no dams, no channelization, no riverside development along the stretch that traces the park line from Bear Creek down to West Glacier. The Middle Fork rises in the Great Bear Wilderness and runs roughly 92 miles, gathering snowmelt from the Lewis Range before joining the North Fork near Blankenship Bridge. Its water runs cold into August because much of it left a snowfield weeks earlier. Guides on any overnight rafting trip glacier national park itinerary will point to that fact when they hand out wetsuits in seventy-degree air. The canyon itself is the record of the region's geology. Cliffs of Precambrian Belt Supergroup rock — argillite, siltite, stromatolitic limestone laid down over a billion years ago — rise directly from the waterline, tilted and stacked by the Lewis Overthrust, the same fault that gave the park its peaks. Bonecrusher, Jaws, Pumphouse and Could Be Trouble are the named rapids along the whitewater section, Class II to Class III at typical summer flows. Below them the current flattens into long green pools where the scenic float trips run. Human history braids through the corridor as tightly as the channels do. The Great Northern Railway laid track along the Middle Fork in 1891 under John F. Stevens, who located Marias Pass just upstream; freight trains still shadow the river on the south bank. The park was established in 1910, and the highway, rail line and river have shared the same narrow canyon ever since. Bald eagles nest in the cottonwood galleries. Harlequin ducks — a species that winters on the Pacific coast and breeds on fast, clean mountain water — return to these riffles each spring, and their presence is treated locally as a measure of the river's health. What draws visitors to overnight rafting trip glacier national park tours today is less the whitewater than the vantage. From a raft the mountains read differently: no shuttle queue, no pullout, no windshield. The Apgar and Snowslip formations show their color bands from water level, and Glacier's south wall stands unbroken above the trees. Entry to the park itself is 135 USD (Standard vehicle pass ($35) plus $100 non-US resident surcharge per person), and the park operates 00:00–23:59 daily, though the river runs on its own schedule of snow and season.