Rising as a small stream in the valley to the south, the Salmon winds 420 miles across Idaho before flowing into Snake River. Discovered in 1895 by Lewis and Clark, and explored with great difficulty by fur traders and prospectors, the Salmon drains a vast tangle of rugged mountains and deep canyons. Until after 1950, boats could not ascend the main canyon, so the Salmon got the name "river of no return". Large tracts of untamed wilderness are still found in the Salmon River mountains.