Flathead Lake in northwest Montana is the largest natural freshwater lake west of the Mississippi; slightly larger than Lake Tahoe at 27.3 mi. Long, 15.5 mi. Wide, and max depth of 370.7 ft.
As one of the cleanest in the world, Flathead Lake is perfect for swimming. Take a dip in and cool off on those hot summer days in some clear, clean, and crisp water!