This spectacular river canyon cuts the only sea-level route through the Cascade Mountain Range.
It flows for more than 1,200 miles, from the base of the Canadian Rockies in southeastern British Columbia to the Pacific Ocean at Astoria, Oregon, and Ilwaco, Washington. The Columbia has ten major tributaries: the Kootenay, Okanagan, Wenatchee, Spokane, Yakima, Snake, Deschutes, Willamette, Cowlitz, and Lewis rivers. Its most important tributary, the Snake, runs through the deepest gorge in North America, Hell's Canyon -- which is 7,900 feet deep.
The once-untamed Columbia, the greatest river in the Pacific Northwest, is now harnessed for human purposes by a series of dams. Starting in Canada, it crosses Washington from north to south and becomes the Washington/Oregon border for several hundred miles before emptying into the Pacific Ocean.