The trail to Castle Peak follows Pearl Pass Road, a 4WD dirt road that follows Castle Creek through a forested valley with small open meadows and past a cascading waterfall just below timberline. Depending on road conditions and type of vehicle, you could drive up the 4WD road making the approach shorter, however, you must cross the creek at the first falls where there is only a footbridge for hikers. Beyond the falls the trail steadily climbs above treeline and into an alpine basin below Castle Peak. The trail ascends east of Montezuma Basin and follows a ridge to the summit.