Mount Diablo Four Peaks Loop

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This 15 mile loop visits the summits of Mount Olympia (2,946'), North Peak (3,557'), Mount Diablo Summit (3,849'), and Eagle Peak (2,369'). Expect lots of views and a variety of scenery, but also a lot of climbing.

Most of this run is steep and sunny, so bring plenty of water and sun protection, and avoid this run in the heat of summer.

Park at the end of Regency Drive. From here, run downhill to the main trail and turn south toward Mount Diablo onto Donner Canyon Road. The mountains you'll be climbing loom ahead of you. Follow the trail along a fairly gentle climb passing several trail junctions along the way. At 1.5 miles, turn left on Cardinet Oaks Road. Here, the views open up and things start to get steep. After about three-quarters of a mile, turn right on the singletrack Olympia Trail. Around three miles into the run, the Olympia Trail eventually turns into Mount Olympia Road. Stay on the road for half a mile, then follow the Zipper Trail where it breaks off to the left.

When the Zipper Trail ends on the East Trail, turn right and head toward the summit of Mount Olympia about four miles into the run. Here you'll have amazing views. From the summit of Mount Olympia, take the North Peak Trail to the south for about three-quarters of a mile. At 4.8 miles make a detour heading east on North Peak Road to the summit of North Peak. It's a road, but it's so steep and rugged that you might need to use your hands.

After taking in the views, backtrack along the road downhill—watch your footing. Stay left at the junction with North Peak Trail continuing downhill to Prospectors Gap. Look for the North Peak Trail (a different one from earlier—yes it's confusing) at this big intersection, and take it south to Devils Elbow next to the paved Summit Road. At Devils Elbow, turn right onto the Summit Trail and follow it to the summit of Mount Diablo. This is the highest point along this route, and the views are great! With a visitor center and parking lot, the summit can be pretty busy, but there are water fountains and bathrooms available here as well. You should be able to find Mount Tamalpais on the horizon to the north, and on very clear days you can see the peaks of the Sierra Nevada to the east.

The next part of the run crosses parking lots and campgrounds, so check your map to make sure you're on the right track. Take the Summit Trail back down the way you came; when it gets to the paved Summit Road, cross the road and run across the large parking lot on the other side. Find the Juniper Trail on the opposite end of the parking lot. Take the Juniper Trail to Juniper Campground. Running through the campground to find Deer Flat Fire Road on the other side. Follow Deer Flat Fire Road, passing the turnoff for Burma Road and descending to Deer Flat.

At Deer Flat, turn right on Meridian Ridge Fire Road, and climb to Murchio Gap, about three-quarters of a mile. If you're exhausted and need to bail, you can take Back Creek Trail from Murchio Gap and then Back Creek Road to Regency Drive, skipping Eagle Peak. If continuing on, at Murchio Gap, take the Eagle Peak Trail. The trail follows a steep-sided ridge up and over Eagle Peak, with great views on both sides. Stay on the trail for a total of about three miles.

Eagle Peak Trail ends down in the grasslands and oaks at the base of the mountain. Turn right on Bruce Lee Road, cross Back Creek, then turn left on Back Creek Road. Back Creek Road ends at Donner Canyon Road, which you can follow back to where you started.