Total Round Trip Distance & gain-21 miles & 4,600-ft
Distance to Upper Slate Lake 9.2 miles and 2,370-ft
Upper Slate Lake to Peak L--- RT and & gain 3.5 miles & 2,500-ft
From the Boulder Creek TH, hike southwest 1.9 miles to the signed Gore Range Trail (39°43.364' N, 106°10.991' W.) Hike the Gore Range Trail north 3.5 miles to the signed Slate Creek Trail (39°45.772' N, 106°11.686' W.) Take the Slate Creek Trail 3.25 miles to Slate Lake or Lower Slate Lake (39°44.713' N, 106°14.592' W.) There is good camping here. From here, the trail becomes steeper, and the last mile to Upper Slate Lake will cover 1000-ft. When you reach the Upper Slate Lake, look for good camping about .2 miles southwest of northeasterly end of the lake (39°44.452' N, 106°15.830'.) I recommend this to be “base camp” for the next few days.
From a base camp at Upper Slate Lake locate a faint trail that skirts the southern side of the lake and follow it past the west end of the long lake. This trail is tough to locate. Don’t attempt at night. After about a half-mile mile of hiking through dense lakeside foliage, the trail gradually makes its way and parallels Slate Creek above the long lake. Again, the trail here is challenging to follow but it is your only way through the downfall and marshy areas; wear gaiters.
As the trail reaches the creek, follow it up through some slabby ramparts to finally reach a place to cross Slate Creek (39,44.053’ N,-106,16.365, W.) There are a few different places to cross the creek.
Next, ascend Peak L’s south slope almost 1,700-ft to a saddle between Point 12,730 and the summit- class 2+. From here, hike class 1 terrain past a large gendarme on the right to an obvious place where the southwest ridge on Peak L terminates (12,800-ft). This is where the fun begins.
From here, study the steep slabs above you. Climb the slabs via some perfectly placed crack systems, back to the ridge crest-steep-semi exposed class 3. Continue to the knife-edge and survey the traverse, the view is daunting. The left side is 500/600 ft of exposure and the right side is 300/400-ft of exposure, it is solid. Most will feel more comfortable “scooting” across this portion of the ridge. It is not a sexy way to climb but it feels safer this way. Some may have balls the size of Texas and feel more comfortable grabbing the ridge crest and traversing.
After the airy knife edge, expect a steep class 3 down climb to a saddle of sorts and also expect another daunting view of the remainder of the route up the summit block. The west face of Peak L consists of almost vertical slabs of granite, broken up by a series of crack systems. At this point, some may be more comfortable using a rope here, for it is easy to stray from the true class 4 line up through the cracks. Locating the correct line takes some patient route finding, however there is a good line and if you hit it just right, you won’t need a rope unless the exposure gets to you.
Climb the west face to the summit-exposed class 4.
Descend your ascent route or take a detour and descend a steep gully all the way down the slope.
Helmet, crampons and ax before mid August.