"An 8,744-foot cascade volcano, Diamond Peak dominates this wilderness, although four other mountains here rise above 7,000 feet. The peak is surrounded by several sizable glacial lakes like Crescent, Odell, and Summit, plus numerous, smaller, glacial-cirque lakes, all within the wilderness boundary. Many of the larger lakes contain stocked trout populations, with brook trout and rainbow trout the most common species.
Given the abundance of water—bigger lakes, pothole lakes, and small, water-filled depressions—mosquitoes can be fierce in early summer. Some 14 miles of the Pacific Crest Trail traverse the wilderness, in addition to 38 miles of other trails. The highest-use areas—Marie, Divide, and Rockpile Lakes—are popular base camps for the climb up Diamond Peak. This trail guide contains four trails ranging from 4 to 18.2 miles in length."