The Eagle Lakes Trail (431) is mostly forested, transitioning from mature pine to subalpine fir & larch, finishing above treeline at Horsehead Pass. On hot summer days, the trees provide welcome shade. In early summer, the hike has a flower show right from the trailhead (elevation 4760 feet), followed by a view up the Martin Creek valley.
Crater Creek is bridged and the junction with the Crater Creek Trail is reached at 0.7 mile (elevation 4900 feet). Continuing the climb through the forest with a couple of small meadow crossings, the Martin Creek Trail junction is reached at 2.2 miles (elevation 5590 feet).
The climb continues with a couple of switchbacks in the gradually thinning forest and passes a campsite at 3.0 miles. Shortly after the campsite, the forest becomes sparser, crossing small meadows with views upvalley and downvalley. Then it's back into the forest along a well constructed tread with many turnpikes.
At 5.5 miles (elevation 7110 feet) is an overlook of Eagle Lake with benches. 5.7 miles in (elevation 7000 feet) the trail crosses Eagle Creek on a bridge, passing two campsites and a motorcycle "parking lot". After crossing a substantial rockslide on a good trail and switchbacking through larch forest and scree slopes the trail reaches Horsehead Pass at 6.8 miles (elevation 7540 feet). Views abound to the southwest and northeast. Note: In late spring the cornice on the northeast side of the pass can be an impediment to all users.
Along the Eagle Lakes Trail, access to the lakes are via one old trail and two current trails.
At 4.7 miles from the trailhead (elevation 6710 feet) is the junction with the "Not Maintained" old trail to Eagle Lake. While not formally maintained, volunteers have kept it usable for hikers and stock. This descending traverse trail reaches the east side of Eagle Lake (elevation 6490 feet) in 0.4 mile.
At 5.7 miles from the trailhead (elevation 7050 feet) is the junction with the Upper Eagle Lake Trail (431A). The Upper Eagle Lake Trail can be difficult to discern from the myriad of social trails in the area. It initially traverses well above the pond and then climbs over a small secondary ridge before reaching Upper Eagle Lake in 0.5 mile (elevation 7110 feet). Just before the lake is a large horse camp and a mountain toilet. Almost every level spot around the lake is a campsite.
Note: The user trail to the pond below Upper Eagle Lake is being revegetated, as the pond is not that attractive for activities (mud bottom, marshy edged, and a mosquito hatchery).
At 6.3 miles from the trailhead (elevation 7050 feet) is the junction with the formal trail to (lower) Eagle Lake (431B). This trail switchbacks down through a steep meadow, beautifully flowered in early summer, and into the larch forest, which is golden in the fall. After a descending traverse with a crossing of Eagle Creek (difficult in spring), it reaches the horse camp on the north side of Eagle Lake at 0.9 mile. The trail continues another 0.5 mile around the lake to more campsites and the end of the informal "Not Maintained" trail.
As the Eagle Lakes trail is a popular multi-user trail, expect to meet horses, bicycles, and motorcycles on the weekends.