Despite its devilish hot name, Mount Diablo has a cooler, splashier side. Heavy winter rains create a collection of six scenic waterfalls encircling the mountain’s rugged northern canyons. Take the grand tour on this 5-mile loop with a gentle climb up Donner Canyon Road to the junction at Cardinet Oaks Road. Head left and cross (or wade through!) the stream to the first hidden waterfall (on the left), a perfect spot to take a tranquil breather before continuing the strenuous ascent through pine, sagebrush, and paintbrush blooms to rocky Middle Trail and then Falls Trail. The exposed ridgeline ascent is steep and precariously narrow, with unimpeded previews of each of the next five falls on the crescent circuit as well as sweeping panoramas to the north. Take a moment to soak in the canyons’ sprouting Irish grandeur on one of many grassy knolls before descending right on Meridian Ridge Road and left back onto Donner Canyon to finish the loop. Be prepared for mud and ankle-deep stream crossings after steady rain.
Note: Parts of this trail can be slick and slippery, so wear good shoes and avoid days that are ceaseless downpours. From Walnut Creek, take Ignacio Valley Rd. 8 miles east to Clayton Rd. Turn right onto Clayton and follow it as it turns into Marsh Creek Rd. (do not turn at the first Marsh Creek Rd.) and intersects Regency Rd. The trailhead at Regency Gate is at the end of the road. Free parking available on the street. Hike through Regency Gate and follow Donner Canyon Fire Road on the left for 1.5 miles to Cardinet Oaks Fire Road junction. Turn left onto Cardinet Oaks Fire Road and then right onto Middle Trail 0.5 mile later, which turns into Falls Trail. Follow Falls Trail around the upper canyon until you circle back to Meridian Ridge, where a right followed by a left back onto Donner Canyon Fire Road leads back to Regency Gate. No dogs.