Grand Tetons, Wyoming. Calm water in a side channel of the Snake River creates a perfect mirror image of the Teton Range in Grand Teton National Park, Wyoming. With its headwaters on the Yellowstone Plateau 40 miles to the north, the Snake River is one of the great rivers of the West. It eventually flows into the Columbia River 700 miles downstream from this location after plunging through Hells Canyon along the Oregon- Idaho border.