[3][4] Diamond Peak is a shield volcano formed as the entire Cascade Range was undergoing volcanic activity and uplift.

[1] Nearly the entire Diamond Peak Wilderness is covered with mixed stands of mountain hemlock, lodgepole and western white pine, and silver, noble and other true firs.

[1] Alpine flowers, including varieties of mimulus, trillium, lupine, penstemon, heather, and Indian paintbrush, are common along trails, lake shores, streams and in the meadows.

Black bear and small mammals including marmots, snowshoe rabbits, squirrels, pine martens, foxes, and pikas inhabit the area all year long.

[2][5] Recreational activities in the Diamond Peak Wilderness include hiking, horseback riding, camping, hunting, fishing, and mountain climbing.