Rising sharply from the western face of Castle Rock, the Big Deal Pinnacle—also known locally as Square Diehl—offers an inviting yet boldly authentic trad climb just steps from Boulder’s urban edge. Its unmistakable tower juts skyward, daring climbers to leave the familiar trails behind and engage with a route that balances hands-on crack climbing with technical face moves. This two-pitch classic stands about 150 feet tall, delivering a 5.9 difficulty that feels approachable yet demands focus and readiness for subtle challenges.

Your journey begins by choosing your approach pitch. Options include the first pitch of Polyester Leisure Suit, the West Face’s initial pitch, or a crack system immediately left of Polyester Leisure Suit but right of the adjacent wide slot. The last is recommended for those looking to stretch into new terrain with a solid 5.7 rated approach that protects well, easing the transition to the heart of the climb.

Once at the anchors perched near two sturdy trees, the route unfolds up the pinnacle’s center face. A series of cracks yield to a perfect hands and wide-hands corner that climbs roughly 30 feet before reaching a horizontal, leftward rising traverse. This traverse—accessible also from below the face—marks the boundary between sustained crack climbing and a more exposed edge traverse.

From this point, climbers follow the pinnacle’s right edge, crossing back to the right on a second rising traverse along a horizontal break. While these moves appear exposed, both traverses offer credible protection, enough to maintain confidence but guaranteed to sharpen your attention. The final stretch involves climbing cracks on the right side of the tower or moving onto the west-facing slab en route to the summit.

Summit rewards come with a catch: no solid belay spot directly on top. Instead, a shoulder on the climber's right features reliable cracks, blocks, and horns where a secure belay station can be set with some care and experience. Planning your anchor placement here is crucial before beginning your descent.

Descending offers multiple options. The standard rappel is from the summit down the established West Face route. For those seeking an alternative, a 5.6 to 5.7 downclimb exists to the trees below the climb’s left side, providing a hands-on exit that retains the flow of the rock. Another rappel possibility is off anchors positioned above Bailey’s Overhang or Curving Crack, slightly easier and more straightforward.

Protection is straightforward but demands thoroughness. A standard rack up to 3.5 inches covers the majority of placements, with extras sized for hands to wide-hands cracks. Long slings are essential to reduce rope drag on the exposed traverses and awkward placements. Expect tight placements in places, so solid trad skills are non-negotiable.

Castle Rock itself offers a distinctly rugged outcrop within reach of Boulder, making this route accessible yet surrounded by wild feel. The granite’s texture changes with the sun, cooling quickly in the shade of late afternoons. The western aspect means early day climbing can be chilly, while midday heat can bake exposed slabs; spring and fall offer the best blend of moderate temperatures and steady weather. The rock can be dusty after dry spells, so brushing holds before committing is advised.

Final tips: pack water and snacks for the approach and climb, check weather forecasts carefully, and don’t underestimate the mental edge this route cultivates—traverses demand a calm mind and steady feet. Big Deal Pinnacle is a climb that rewards preparation and respect, beckoning climbers to engage in a route where the natural rock feels alive, pushing steadily upward in a dance between crack and face, challenge and safety.