Diamond Peak is the highest summit in Idaho’s Lemhi Range and the third-highest peak in the state, rising to 12,202 feet in the Rocky Mountains. It stands above the Little Lost River valley, east of Borah Peak in the Lost River Range, and is also the highest point in the Caribou–Targhee National Forest. Its importance is chiefly geographic: it dominates the Lemhi Range skyline, marks the top of its own range, and stands as the highest mountain across a broad surrounding stretch of national forest. The nearest higher summit is Mount Church, farther west.