Archipelagos and narrow channels mark each end of the Strait of Georgia, the Gulf Islands and San Juan Islands in the south, and the Discovery Islands in the north. The main channels to the south are Boundary Pass, Haro Strait and Rosario Strait, which connect the Strait of Georgia to the Strait of Juan de Fuca. In the north, Discovery Passage is the main channel connecting the Strait of Georgia to Johnstone Strait. The strait is a major navigation channel on the west coast of North America, owing to the presence of the port of Vancouver, and also due to its role as the southern entrance to the Intracoastal route known as the Inside Passage.