Lake is one of a series of lakes on the Gravely Ranch between Centennial Valley and the Madison River Valley in Montana.
Elk lakes nearby also are worth fishing.
Access to Hidden Lake is from Highway 20, south of Henry's Lake in Idaho. It's about a 25-mile drive on a good gravel road over Boot Jack Pass, a beautiful drive across the Continental Divide and through the Red Rock Bird Refuge. Boat rentals, lodging, and camping are available at Elk Lake Camp. You'll need to carry your float tube about half mile from the parking area at Hidden Lake. Hidden Lake offers good wet-fly fishing with sinking lines.