Chouinard's Crack stands out as a rugged test of traditional climbing skill on the mid-left side of the Upper Tier at Boy Scout Rocks, located within Mount Diablo State Park. This 50-foot sandstone crack beckons climbers looking for a precise balance of technical movement and gear finesse, all framed by sweeping vistas of the San Francisco Bay Area. The climb begins with solid holds, but as you reach the crux roughly 25 feet up, the crack tightens and demands a keen eye for subtle foot placements and confident hand jams. A nearby tree, rooted half-way up the route, offers both a visual landmark and a useful anchor point, especially when preparing for a top rope setup with an extended sling.

The Approach unfolds along well-used trails that thread through open chaparral and pockets of oak, delivering a straightforward but unrelenting 20-minute hike to the base. Once on the rock, the sandstone’s texture engages the fingers and toes with a blend of gritty edges and delicate seams. Your protection must be chosen carefully: small to 3-inch cams fit best, and carrying a long sling—30 feet or more—is key to safely extending your anchor or wrapping the tree to avoid rope drag.

Expect a route that rewards patience and thoughtful gear management, as protection spots can be a challenge before an exposed run-out near the crux. Climbers under 5.9 will find the grade solid, with some feeling the moves test balance and technique more than brute strength. The crack’s slightly angled orientation catches morning sun, making early climbs comfortable, while afternoon ascents benefit from cooler shade that bulb up the rock faces as the sun moves westward.

Getting down means a single rappel off the tree, but rope management is critical due to the sling length and sandy surfaces that can wear equipment. Bringing sturdy shoes with sticky rubber is advised, alongside a helmet because loose sandstone flakes are a real hazard here. Chouinard's Crack offers a concentrated burst of climbing adventure that challenges your ability to read the rock and place dependable pro, all while soaking in one of California's classic sandstone settings.