Boulder Glacier, Alpine glacier on Mount Baker, Washington, United States

Boulder Glacier is a mountain glacier extending from the summit crater between Grant Peak and Sherman Peak down to 5,000 feet on Mount Baker's southeast slope. The glacier can be accessed via Boulder Ridge Trail 605, which passes through forests of Pacific silver fir trees.

Between 1850 and 1950, the glacier retreated significantly, losing about 2600 meters in length before advancing again during cooler weather conditions. This pattern of retreat and advance reflected larger climate swings that shaped the alpine region.

Scientists use this glacier to study climate patterns and environmental changes across the Cascade Range. The research here helps explain how temperature shifts affect alpine ecosystems and mountain landscapes.

The best time to visit is during summer months when snow has melted from the higher trails. Weather at elevation can change quickly, so visitors should be prepared for variable conditions and bring appropriate gear.

The lowest 1,000 feet of the glacier was observed in 2005 to be stagnant, gray with rock debris and with few crevasses, and likely to disappear. On the west side of Boulder Creek, the recent recession has exposed a small waterfall.