Flathead Lake is a large natural lake in Northwest Montana and is the result of ice-age glaciers that cut the Flathead Valley and carved the lake. It is fed with fresh water from the Flathead and Swan rivers, covering nearly 200 square miles of Montana. Fish that can be found in the lake include bull fish, cutthroat trout, perch, and whitefish. The lake is a popular attraction for fishermen, boaters, river rafters, and hikers.