Start at the Lava Camp Lake Trailhead at 5,300 feet in elevation. The trail goes southwest from the parking area. At mile 0.2 is the junction with the Pacific Crest Trail #2000. Stay left (south). The trail right goes to McKenzie Pass about 0.5 miles away. At mile 0.9 (5,460 feet) is the junction with the Mattieu Lake Trail #4062. You can go either way – it’s the same distance, but for this hike, I arbitrarily say to stay right. At mile 2.1 (5750 feet) is North Mattieu Lake. There are many nice campsites around the lake and a somewhat sparse forest of pine trees. This can be crowded on summer weekends. At mile 2.8 (6,030 feet) is the junction back to the PCT. A few hundred feet farther is South Mattieu Lake. There are a few campsites around the lake and a little alpine vegetation. Here, there are quite a few people on summer weekends, but beyond here the crowds thin out.