McCullough Gulch Trailhead:
Take CO-9 eight miles South of Breckenridge or two miles North from Hoosier Pass. Turn west on County Road 850 and an immediate right onto a dirt road, County Road 851. This is the standard approach for the popular Quandary Peak and parking along the road may be at a premium. Continue 2.1 miles to the trailhead. Near the 2 mile mark, the road Ys. Take the left. Parking is along the road side before a gated closure.
This road is not often plowed in the winter and may be impassable into late Spring.
From the trailhead, begin on the McCullough Gulch trail, which is easy to follow from the gated closure. Follow this good trail for about 2 miles into the gulch. There are several social trails here, so use your map to judge which one you should take. In general, follow the largest one.
The trail will fade in the upper basin, once you have passed several lakes. Veer toward Fletcher's Northeast Slopes. There is no good trail here, but you will find some segments through the loose rock.
Another option is to use this route from Quandary Peak. This will drop you off higher than the saddle along Quandary's West Ridge, and will require you to gain some extra altitude. However, this route will provide easier travel on a better trail.
Once you gain the ridge, boulder hop to the summit. Return the same way you came.
Round Trip Mileage (McCullough Gulch): 7.0 miles
Elevation Gain: 4,000 feet
McCullough Gulch from the summit of Atlantic. This photo shows the gulch you will travel on the way on this route.