Redfish Lake is an alpine lake in central Idaho, United States, located in the Sawtooth National Recreation Area, at the base of the Sawtooth Mountains in Custer County. It is named for the brilliant sockeye Salmon that once returned from the Pacific Ocean in such massive quantities that the lake shimmered red during spawning season. However, these fish are now on the endangered species list.
The north end of Redfish Lake hosts many developed recreation opportunities, including the Redfish Lake Lodge (restaurant, cabin and boat rentals) and Forest Service campgrounds, boat launch, day-use areas and a visitor center. Redfish Lake is about a mile upstream of the smaller but equally picturesque Little Redfish Lake. The easiest way to reach the highest peak in the Sawtooths, Thompson Peak, is from the Redfish Lake Trailhead.