Flathead Lake is the largest natural freshwater lake in the western part of the contiguous United States. With a surface area of between 191.5 sq mi and 197 sq mi, it is slightly larger than Lake Tahoe. The lake is a remnant of the ancient inland sea, Lake Missoula of the era of the last interglacial.
The water is so transparent makes it seem like a quite shallow lake. In fact, it’s very deep.
Its known maximum depth is 370.7 ft making it deeper than the average depths of the Yellow Sea or the Persian Gulf. The lake was raised 10 ft by Kerr Dam.It is one of the cleanest in the populated world for its size and type.
