Route 3 crosses a region known as the Rhododendron Flats, where these wild plants flower in profusion in mid-June, leading up to Allison Pass (1 341m/4 400ft). The park is home to subalpine-type landscapes: the western slopes are covered with the damp, dense vegetation of coastal British Columbia; the central area reflects the transitional zone; while the eastern part with its dry and arid sagebrush vegetation is typical of the interior of the province.