What is the appeal of Flathead Lake as a Summer vacation destination?
Flathead Lake is the largest natural freshwater lake West of the Mississippi in lower 48 contiguous states, with over 200 square miles of water and 185 miles of coastline.   It is a beautiful lake, surrounded by the tall and impressive Mission Mountains on the east and the smaller Salish Mountains to the west.  It borders several Indian reservations on the Southern end of the lake.

The lake offers an abundance of Summer activities including: sailing, boating, swimming, and camping.  The lake offers excellent fishing and the fish species in the lake consist primarily of lake trout, pike, yellow perch and whitefish, with some rainbow trout, bass, and salmon. The lake trout can reach monstrous sizes, frequently exceeding twenty-pounds.

Overall, Flathead Lake is one of the premiere recreational and fishing lakes in Montana. It is popular for both fishing and pleasure boating and  the sheer beauty of the lake makes it a memorable one regardless of which activity is pursued.
Instruction: What is the appeal of Flathead Lake as a Summer vacation destination?
Context: 
Response: Flathead Lake is the largest natural freshwater lake West of the Mississippi in lower 48 contiguous states, with over 200 square miles of water and 185 miles of coastline.   It is a beautiful lake, surrounded by the tall and impressive Mission Mountains on the east and the smaller Salish Mountains to the west.  It borders several Indian reservations on the Southern end of the lake.

The lake offers an abundance of Summer activities including: sailing, boating, swimming, and camping.  The lake offers excellent fishing and the fish species in the lake consist primarily of lake trout, pike, yellow perch and whitefish, with some rainbow trout, bass, and salmon. The lake trout can reach monstrous sizes, frequently exceeding twenty-pounds.

Overall, Flathead Lake is one of the premiere recreational and fishing lakes in Montana. It is popular for both fishing and pleasure boating and  the sheer beauty of the lake makes it a memorable one regardless of which activity is pursued.