I-5 travels along the eastern shore of Lake Samish before turning west to follow Chuckanut Creek through a narrow valley formed by Chuckanut and Lookout mountains in Lake Samish State Park. At Lake Padden, it turns north and enters the city of Bellingham, intersecting SR 11 east of Fairhaven and the Alaska Marine Highway terminal. The freeway travels along the east side of Sehome Hill and downtown, passing the Western Washington University campus and several intersections with downtown streets. Northeast of downtown Bellingham, I-5 intersects SR 542 (the Mount Baker Highway) and turns west to meet SR 539 at the Bellis Fair Mall. The freeway heads northwest and leaves Bellingham after passing Bellingham International Airport, entering the predominately rural part of the Fraser Lowland region. I-5 continues northwest along the railroad, crossing the Nooksack River on a pair of truss bridges near downtown Ferndale and reaching a junction with SR 548 north of the city. SR 548 continues along the highway and travels west towards the Cherry Point Refinery and Birch Bay.