protected sea route along the W coast of North America, from Seattle, Wash., to the N part of the Alas. panhandle: the route uses channels and straits between islands and the mainland: c. 950 mi (1,529 km) long
See Inside Passage in American Heritage Dictionary 4
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.