Few people know the grandeur of Idaho’s Pioneer Mountains. This gem of a lake is a well-kept secret because it’s far from any population centers. But don’t let the drive dissuade you. Plan a nearby camping trip or weekend in Sun Valley, and suddenly, a trip to Boulder Lake becomes a realistic day hike.

Tucked away in some of Idaho’s tallest Peaks, Boulder Lake is surrounded by a rim of jagged, sky-scraping peaks that will leave your eyes popping out. You’ll find extraordinary views of the Devil’s Bedstead and other unnamed peaks topping out near or above 12,000 feet.

The trail begins at a pull-out along Wildhorse Creek Road. You will immediately have to cross Wildhorse Creek, hike across the the floodplain, and begin trekking up switchbacks into a slot canyon. At about two miles in, the views of the stunning alpine scenery begin to unfold. The last half of the trail is primitive, but you can easily follow the route through avalanche chutes, stands of alpine fir, and boulders to the lake. There are a few primitive campsites available, as well as off-trail opportunities to explore the surrounding basin and lakes.

Don’t plan on visiting until the end of July. Snow lingers in this north-facing cirque well into the summer.


3.8 miles (one way)

Elevation Gain

2,226 feet


From Ketchum, drive northeast on Trail Creek Road for 22.5 miles, passing over Trail Creek Summit into the Lost River Basin. Turn right on Wildhorse Creek Road. Drive approximately 7.7 miles to the trailhead, bearing right at the junction with East Fork Lost River Road. The trailhead is located at a pullout on the right side of the road.


Forest Service: Challis National Forest

USGS Quad(s): Standhope Peak, Phi Kappa Mountain

Maintenance Report

The first 2 miles of trail 4057 were maintained by Forest Service crews in 2010. However, at 2.5 miles, the trail becomes more primitive. Follow the most prominent foot path, avoid cutting switchbacks, and stay off of user-created trails to protect the fragile environmental conditions.

Land Status

The Pioneer Mountains are a proposed wilderness area.