It's been a long time since I've been to Mt. Diablo State Park. It's one of my favorite places, but so are all of the other parks around here. So, I got my trusty map and planned a hike. I wanted to do a loop hike, and I found a nice route around Pine Canyon. Most of this route is on fire roads, but Secret Trail is a single track that winds through some nice forest. This was a busy route, filled with hikers and runners of all ages.
The trailhead is located at the end of Green Valley Road in Alamo. There is parking there, and bathrooms, but you'll need to pay the $6 fee in to a little box, and put your reciept on your dash.
Distance: 6.14 miles
Ascent: 2905 feet
Descent: 2984 feet
Calories burned: approximately 660
Route:
Start out at the Marcedo Ranch Trailhead (End of Green Valley Road in Alamo)
Bathrooms, picnic tables, $6 parking fee
Take Wall Point Road
Bear Right at split between Dusty Road and Wall Point Road
Keep on Wall Point Road past Emmons Canyon Road
Climb to Wall Point at 1600 feet
Keep Left on Wall Point Road toward Secret Trail
Left on to Secret Trail
Left on BBQ Terrace Road
Left on to Stage Road
Left on to Dusty Road
Right on Well Point Road back to parking lot
Notable Scenes:
Sun hitting the back side of these Oaks on the hill next to Wall Point Road 
You'll see this nice cluster of Oaks as you climb Wall Point Road, just past the cow gate
Perching Scrub Jays on a Manzanita - Wall Point Road 
Secret Trail - The only single track trail on this hike Full Photo Gallery