Flag Hill Loop, Sunol Regional Wilderness

The hike begins from the trailhead behind the large green barn -- Sunol Headquarters. Take the bridge behind the barn across the Alameda Creek. Turn left on opposite side.

Take short, flat trail till you see a sign for Flag Hill Trail. Turn Right.

Start climbing up toward Flag Hill. You'll pass through a gate and a junction with the Shady Glen Trail; don't turn on it.

This climb is steep and rocky in places; you'll need to watch your step in many places. It's OK to stop and rest to catch your breath. The higher you go, the better the scenery gets.

After about a mile you'll reach Flag Hill summit. Go left to explore the rocks at Flag Hill.

Awesome views overlook the Calaveras Reservoir and the nearby Diablo Range.

Be very careful on the rocks.

At the Flag Hill Road junction, bear left and head downhill for about a mile.

This will be fairly steep in places, so mind your footing.

The trail ends at an intersection near a large, gnarled tree. There may be cattle resting under it.

High Valley Road is the intersection nearest the large tree. Turn right and take High Valley for about a quarter mile -- bear right at the first split in the trail -- to Hayfield Road.

Hayfield Road passes between an old barn on the left and a picnic shelter on the right. It then curves to the right and heads downhill for about a mile back to the bottom of the hill near Alameda Creek. See if you can spot a cactus grove on your right on the way down; with any luck a cacti might be in bloom.

At the bottom of the hill, turn right, go a short distance and turn left at the bridge returning to the Park HQ.