Rock Island Lake is a small alpine lake in Elmore County, Idaho, United States, located in the Sawtooth Mountains in the Sawtooth National Recreation Area. The lake is accessed from Sawtooth National Forest trail 459 along Johnson Creek.Rock Island Lake is in the Sawtooth Wilderness, and a wilderness permit can be obtained at a registration box at trailheads or wilderness boundaries. There is a single rocky island that is less than 200ft long that gives the lake its name.
