Lake Union is a freshwater lake entirely within the Seattle, Washington city limits and a major portion of the Lake Washington Ship Canal. Its easternmost point is the Ship Canal Bridge, which carries Interstate 5 over the eastern arm of the lake and separates Lake Union from Portage Bay. Lake Union is the namesake of the neighborhoods located on its east and west shores: Eastlake and Westlake, respectively. The northern shore of the lake is home to Gas Works Park.