the western mountain system's coast mountains are the westernmost range of the pacific cordillera, running along the western shore of the north american continent, extending south from the alaska panhandle and covering most of coastal british columbia. the range is covered in dense temperate rainforest on its western exposures, the range rises to heavily glaciated peaks, including the largest temperate-latitude icefields in the world, and then tapers to the dry interior plateau on its eastern flanks, or to the subarctic boreal forest of the skeena mountains and stikine plateau.