0 km: Trailhead and parking, N22200-E20500. Good trail climbs steeply in alder and pine stands, switchbacking in long, smooth strides.
1.4 km: Small creek (the only water on the trip until you get to the small muddy tarn beyond the pass). Another 100 m farther is a wooden bench. At 2.1 km and 2.5 km in summer there are dry tiny creek crossings.
3 km: Junction to Walter Cobb Lake. The tiny tarn is 500 m off the main trail. Keep climbing on the main trail through alpine meadows up switchbacks to the pass.
4 km: Wow! The first look at Cobalt Lake with Brenta Spire is wonderfully unique. The pass is on the wide, smooth Black Forest Ridge, N23100-E20500. Turn north (right) and hike along the gentle ridge for just over 1 km and the trail disappears in alpine meadows. (Don’t descend straight off the ridge from the pass and go directly toward the lake. Unseen from the ridge, the slope rolls away into a very steep and unstable route.)
6 km: After hiking north along the scenic ridge for 1km, gradually descend in the open alpine. Head northwest (left off the ridge) away from Cobalt Lake to the headwaters of Vowell Creek. Walk north along a small creek in the flat alpine to a tarn. Cairns may mark the route. The route by the tarn takes a sharp U-turn. Head south now toward a rocky notch and descend 150 m (500 ft.) over the moderate slopes to the valley below Cobalt Lake. Routefind south to a short waterfall streaming off the rocks from the lake above you. Follow the creek by the waterfall uphill to the lakeside.
8.5 km: Cobalt Lake, N23100-E17400. The view of the spire at the lakeside is not nearly as spectacular as it is from the ridge high above. The lakeside features gigantic boulders and gravel with few plants. Camping is not allowed at the lakeshore.