Green River Bastion Boulders

Green River Bastion Boulders, also known as Pemberton Boulders or GRB, is an expansive forested boulder field below Green River Bastion. The area is organized into four sectors: Mothership Boulders, Slug Boulders, Cosmic Boulders, and Lost Boulders.

The area offers roughly 30 bouldering problems, with grades ranging from V0 through V6 in the current problem distribution; one additional problem is shown at V8. Slug Boulders is the largest sector with 20 problems, while Mothership has 4, Cosmic has 6, and Lost has 1. Individual boulders reach about 3–5 m.

Approach from the dirt parking area used for Green River Bastion, then walk north beside the railway. The boulders lie on both sides of the tracks. For Slug Boulders, cross to the east side and follow the trail beginning at the sign marked 92.5. Stay off the railway tracks and keep the area clean.