Colonial Peak, Mountain summit in North Cascades, Washington, US
Colonial Peak is a mountain summit in the North Cascades with steep rock faces and a prominent western ridge. It rises approximately 2,369 meters above sea level and overlooks the Thunder Arm of Diablo Lake.
The peak was first documented climbing by Seattle Mountaineers members in 1931. This early ascent established it as a recognized climbing destination in the North Cascades.
The mountain takes its name from a former mining claim on its slopes, reflecting the region's connection to extraction activities. This heritage is visible in how the landscape bears marks of past human activity.
Climbers reach the summit via the Pyramid Lake Trail near Diablo Dam and follow the West Ridge route through Colonial Glacier. The best season for climbing is from May through September when conditions are most favorable.
The peak is part of a closely spaced chain of mountains that rise steeply from a glacial lake arm. This concentration of high summits within a short distance creates an unusual landscape that rewards those who explore beyond just the main peak.
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