Surrounded by coniferous forest and visible in the skyline from foothills near Eugene, Diamond Peak offers a few climbing routes and can be scrambled.

[17][18] The wilderness area is largely inaccessible by road in the winter season, though its northern side can be reached from Gold Lake Sno-Park on Oregon Route 58.

[21] Formed towards the end of the Pleistocene epoch, these mountains are underlain by more ancient volcanoes that subsided due to parallel north–south faulting in the surrounding region.

[27] Mazama Ash, including pumice up to 32 inches (81 cm) thick as well as plagioclase, pyroxene, and hornblende crystals, can be found throughout the Diamond Peak wilderness area and represents the newest volcanic rock deposited in the region.

[6] Though its lava flows show residual magnetism, the volcano does not display evidence of activity within the past 10,000 years, suggesting that it may now be extinct.

Glaciers also placed both lateral and ground moraines along the lower to middle elevations of the wilderness area, unlayered pebble deposits interbedded with sand and rock.

Both mountains are likely close to the same age as Diamond Peak,[6] and are formed by layers of red and black lapilli, scoria, and volcanic bombs.

[21] Emigrant Butte, a basaltic andesite peak 5.6 miles (9 km) to the south, has been altered more extensively by glaciers, and therefore is likely older.

Mount Yoran is a significantly older mountain made from basaltic andesite lava that has a summit protruding from the northern slope of Diamond Peak.

[30] Yoran and the nearby stratovolcano Lakeview Mountain have similar compositions to Diamond Peak, with dissected cones made of pyroclastic material with embedded lava flows.

[16] Local fauna include common animals found in the Cascade Arc, such as Roosevelt elk, black-tailed deer, red squirrels, snowshoe hares, and a number of bird species.

[34] The closest mining operations took place in the Bohemia district, which lies 20 to 25 miles (32 to 40 km) to the west of Diamond Peak.

[35] Therefore, in the 1980s, surveyors determined that there is little future potential for mineral deposits or geothermal energy resources for Diamond Peak or the wilderness area.

[36] Though Diamond Peak cannot be accessed by paved roads, it lies adjacent on its eastern side to the Pacific Crest Trail.

[12] Another route for climbing Diamond Peak begins from Corrigan Lake, which can be reached by forest roads about 30 miles (48 km) past Hills Creek Reservoir near Oakridge.

[38] The Corrigan Lake Trailhead starts at an elevation of 5,536 feet (1,687 m), following a forested trail toward Diamond Peak's western flank.