Southwest Face

Page Type: Route
Lat/Lon: 44.07530°N / 114.6111°W
Route Type: Scrambling
Season: Summer, Fall
Time Required: Most of a day
Difficulty: Mostly Class 2, with some Easy Class 3 mixed in.
Base of Southwest FaceLooking up from the base of the southwest face.


Due to its location in the heart of the White Clouds, choosing a route to climb Lonesome Peak on a day trip is not obvious at first. There are few trails nearby, but the various ridges located around the peak tend to obstruct a map reader’s intuition (this was an issue for me at least). However, there is indeed a very enjoyable route starting from the popular Fourth of July Creek trailhead, which can be done in a single day by most climbers. There are a couple of route options, but the shortest involves making your way to the Born Lakes, bushwhacking to the base of peak’s southwest face, then scrambling to the summit. The views are great along the way, but to see even more scenery, you should consider returning to the trailhead by a different route (either west ridge, or south ridge).

Getting There

To reach the Fourth of July Creek trailhead, follow Highway 75 about 17 miles south from Stanley (or 45 miles north from Ketchum), then head east on the gravel Fourth of July Creek Road. Continue 10 miles up the road to the trailhead. There you’ll find a good-sized parking lot and an outhouse. The road is pretty rough and wash-boarded, but high clearance isn’t required.
Born Lake PanoramaBorn Lakes, summit just visible on far left.

Route Description

West RidgeNearing the ridgeline.

From the trailhead, the first step is to reach the Born Lakes. There are a couple options for accomplishing this. One way to do it is to follow the trail to Fourth of July Lake, climb to Antz Basin Divide, then descend to Born Lakes (3.7 miles, 1200’ gain to the lakes). But the better option for Peak Baggers is to climb Blackman Peak along the way instead. To do this, follow the Strawberry Basin mine road to the southwest ridge of Blackman, climb the peak, then descend the east ridge briefly before dropping into Antz Basin en route to Born Lakes (3.2 miles, 1600’ gain to the lakes).

Once at the second Born Lake, leave the trail and wander due north through the forest towards a small cirque on the southwest side of Lonesome Peak. Watch for a distinct creek-bed (dried up by late summer) that leads up into the cirque. Once at the base of the peak, there are various route options, but the chute to the left is the most appealing. Climb the scree chute, using tree roots and branches for aid at times. It broadens after a while then reaches the west ridge a few hundred feet below the summit. From this point, it’s a straightforward scramble to the top. (Cheat to the south side of the ridge at first, and then cross over to the north side just below the summit.)

Trip Stats (one way, includes Blackman Peak option):
  • 5.8 Miles

  • 3500’ of elevation gain

  • Plan on at least 600’ additional gain on the way out to climb back over the divide.

Essential Gear

No technical gear required, the route is basic Class 2+ level difficulty. Just dress for the weather. You might to consider carrying a water filter/pump to restock your H2O supply at Born Lakes (both entering and leaving) to save water weight on the approach.