We noticed that you're using an unsupported browser. The TripAdvisor website may not display properly.
We support the following browsers:
Windows: Internet Explorer, Mozilla Firefox, Google Chrome. Mac: Safari.

Flag Hill Loop, Sunol Regional Wilderness

A short, steep hike up Flag Hill promises grand scenery and offers a great way to introduce your kids to hiking.
id_1315502

Content provided by

Rating: 4 out of 5 by EveryTrail members
Difficulty: Moderate
Length: 3.7 miles
Duration: 1-3 hours
Family Friendly

Overview :  Sunol Regional Wilderness is one of the best hiking locales in the East Bay hills northeast of Silicon Valley. This Flag Hill Loop is ... more »

Tips:  Use extreme caution on the rocks at the Flag Hill summit -- a fall could be fatal.

Watch for poison oak on narrow sections of trail.
... more »

Take this guide with you!

Save to mobile
Get this guide & thousands of others on your mobile phone
EveryTrail guides are created by travelers like you.
  1. 1. Download the EveryTrail app from the App Store
  2. 2. Search for the Flag Hill Loop, Sunol Regional Wilderness guide
  3. 3. Enjoy your self-guided tour
Get the app

Points of Interest

1. Sunol Wilderness Headquarters

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.

2. Flag Hill Trail front side

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... More

3. Flag Hill

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

Be very careful on the rocks.

4. Flag Hill Road, back side

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.

5. High Valley Road to Hayfield Road

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... More