Mt. Diablo - the summit.

This trip starts in Donner Canyon at the Regency Drive entrance to the park.
You start out with lots of nice meadows, with oaks, and a burbling creek running beside the road, but about 100 yards in you go up the Back Creek Trail. 

Back Creek Trail is flat and wide to start with, and then it connects with Back Creek and follows it towards the hills. Once you get up closer to the mountains it becomes much smaller, following the hillside just above the creek. It's beautiful listening to the creek as you hike along.

During this first part of the trip you mostly don't have much in the way of views, since you're in the brush in a canyon. Here and there it opens out though, and you'll get good views of Mt. Diablo, Mt. Olympia, and Prospectors Gap, where you're going, as well as back the way you came.

When you come to Meridian Ridge Road be sure to explore this intersection before going on. Meridian Ridge Road goes to the left and right. To the left about 100 yards is a great view of Eagle Peak, and the whole valley. To the right a few yards you'll see  the Eagle Peak Trail cutoff, and over the edge you'll see Mitchell Canyon. A little further on and you'll see Mt. Diablo. 

Right across the road from Eagle Peak Trail you'll find your continuing trail, the Bald Ridge Trail. Before you go up this, take a walk around part of the Eagle Peak Trailhead. This is also a good spot for a short break if you want.

Bald Ridge Trail continues straight up the side of this hill and then follows a ridge towards Prospectors Gap at 2,960'. There are some great views and picnic areas along this stretch of trail, including a meadow along a ridge with views all around.

When you get to Prospectors Gap you connect to North Peak Trail which you'll follow away from North Peak towards the Summit Trail, which then takes you to the summit.

Mt. Diablo: 3,848'.

You circle the mountain to get to the top, where you'll find that the actual summit is inside the building. They built a searchlight on top of it, but the summit clearly shows through. This is a beautiful old building made out of stone. 

Outside and upstairs, the building has an observation deck, with telescopes, so you can really check out the area if you want. You have a 360 degree view here, and on clear days you can see more land area than pretty much anywhere else in the US. You can see the snow on the Sierra's if it's clear out, or the Rancho Seco cooling towers over in the valley. I've read you can even see Mt. Lassen and Mt. Shasta.

Although there are many taller peaks in California, none approach the viewing area of Mt. Diablo.

Heading back to your car is much easier as we're going to go down the fire roads instead of the trails.
Start down the Summit Trail that you came up until you get to Prospectors Gap Road. Follow Prospectors Gap Road to Meridian Ridge Road and follow that to Donner Canyon Road. Donner Canyon road takes you back to your car at Regency Drive.

All the trails have clearly marked signs so there's not much chance of getting lost or anything.
Get out and enjoy yourself.

(*See video below.)

Directions:

From I-680 and Walnut Creek, drive out Ygnacio Valley Road 7.6 miles. 

Turn right onto Clayton Road and drive past Mitchell Canyon road to the second Marsh Creek Road intersection.

There are two choices here:

*For Regency Drive parking continue forward to Regency Drive and turn right. Drive to the end and park.

*Alternate parking - At the second Marsh Creek Road, turn right and drive about 6 blocks to Mountaire Parkway.

Turn left onto Mountaire Parkway. Drive to the end and park. You are right across the canyon from the Regency Drive parking.

The Hike:

Start at the Regency Drive entrance.

About 100 yards in take the Back Creek Trail to Meridian Ridge Road.

At Meridian Ridge Road go right a few feet to where Bald Ridge Trail exits to the left.

Follow Bald Ridge Trail to Prospectors Gap Road.

Go right on Prospectors Gap Road to North Peak Road.

Follow North Peak Road to Summit Trail.

Follow Summit Trail to the top.

When returning follow Prospectors Gap road to Meridian Ridge Road, and Meridian Ridge Road to Donner Canyon Road which will take you back to your car at Regency Drive.

A nice loop of about 12.5 miles and about 3,000' elevation gain.

Mt. Diablo Summit