Inside Passage, natural, protected waterway, c.950 mi (1,530 km) long, threading through the Alexander Archipelago off the coast of British Columbia and SE Alaska. From Seattle, Wash., to Skagway, Alaska, or via Cross Sound to the Gulf of Alaska, the route uses channels and straits between islands and the mainland that afford protection from the storms and open waters of the Pacific Ocean. Snowcapped mountains, forests, waterfalls, glaciers, and deep, narrow channels give the Inside Passage great scenic beauty. It was known to Spanish, Russian, English, and American explorers. It is an important coastal route for Canadian shipping as well as the route generally used by ships sailing between the continental United States and Alaska.