Upper Diamond Lake - 8.1 Miles Round-Trip

Upper Diamond Lake (11,738') is located in a slender cirque under Mt Jasper (12,923') in the Indian Peaks Wilderness. While Diamond Lake is among the area's most popular destinations, few hikers look past or above it to this seldom-visited lake.

Trail Map | Photo Gallery

No trail leads to Upper Diamond Lake, nor is it intuitively reached by following Diamond Lake's inlet - it lies in an adjacent drainage. Cross-country travel and good navigation skills are required.

There are several viable routes: the most efficient one follows the Diamond Lake Trail to meadows just before the lake, then veers off on a steep push through treeline to intercept UDL's outlet, which leads across expansive meadows right to the lake.

Terrain is fairly moderate, save several steep pitches and tangled patches of willow and krummholz. Travel eases considerably above treeline across airy meadows laced with streams and tarns. While Upper Diamond Lake is exceptional, the alpine approach is arguably the most scenic part of the route.

Only experienced hikers should attempt Upper Diamond Lake. Proficiency with maps, compass and/or GPS is required to safely reach and descend from the lake. Distances will vary by route. Avoid trampling sensitive alpine vegetation and walk on rocks whenever possible to minimize impact.

The route described here travels about 1.6 miles and 800' (vertical) off-trail, each way. Much of this time is spent above treeline and travel can be slow, even when terrain is mild. Get an early start to avoid storms and allow plenty of time for the descent: 

The Arapaho Pass Trail rises past the Indian Peaks Wilderness Boundary (.4 miles : 10,385') with a good look at Diamond Lake's outlet-waterfall across the valley. 

It narrows across the midsection of a steep cascade (1 mile : 10,650') to the Diamond Lake Trail split (1.15 miles : 10,752').

The Diamond Lake Trail turns south and drops to a bridge over North Fork Middle Boulder Creek (1.7 miles : 10,602'). It levels through a damp, rooted area (1.85 miles) and turns sharply uphill in a north-facing forest. This steep, twisting segment may be obstructed by deadfall and snow well into summer.

The trail emerges from timber and levels across a large, damp meadow just before reaching Diamond Lake (2.45 miles : 10,940'). It's important to have a good understanding of the route from this point.

You'll need to head NW out of the Diamond Lake basin to intercept UDL's outlet in the adjacent drainage. Finding it is key to reaching the lake.

Leave the trail here (GPS Point #8) and cross the meadow to the far side (2.6 miles). 

Weave through patchy forest and turn up steep, boulder-strewn slopes with great views over Diamond Lake and across the valley to the Arapaho Pass Trail (2.95 miles : 11,250'). Grades moderate into thick krummholz, which you'll have to punch through to reach more open terrain along UDL's outlet. 

Navigation is much easier once along the creek (3.2 miles : 11,390' | GPS #12), though you'll have to clear some willow before emerging by a tarn in postcard-like meadows (3.35 miles : 11,540').

UDL's location is now obvious, and travel eases across expansive meadows to a perennial snowfield just below the lake (3.75 miles : 11,580 | GPS #14). Scale the snow or scramble up talus on either side.

The right (north) side is subjectively preferable. Once above you'll crest through a talus field and drop to Upper Diamond Lake (4.05 miles : 11,738').

Keep close track of your route and mark / record as many points as possible. While you'll have some directional latitude on the way up, the descent back to Diamond Lake must be more precise - especially through willow and krummholz that can obfuscate your original path.