a natural sheltered waterway used as a sea route along the U.S.-Canadian coast, extending from Seattle, Washington, to Skagway, Alaska. 950 mi. (1529 km) long.
In·side Passage (ĭn'sīd') A natural protected waterway extending about 1,529 km (950 mi) from Puget Sound to Skagway, Alaska. It threads through the Alexander Archipelago and is known for its snow-capped mountains, waterfalls, and glaciers.