Flathead Lake (L-III)

The Flathead and Swan rivers supply clean fresh water to Flathead Lake year-round. Created by Ice Age glaciers, almost thirty miles long and fifteen miles across at it's widest point, Flathead lake is the largest natural lake in western U.S. A 160 mile shoreline and water covers nearly two-hundred square miles of Montana - and at 300 feet deep, you'd better restring your fishing reel with some extra line.