Jul 19

Umunhum: The Crown Jewel of the South Bay

Folks living in the South Bay might not know the name “Mount Umunhum”. But if you ask them about “the mountain with the white cube on top”, they will instantly know what you’re talking about. Visible from practically everywhere in San Jose and vicinity, Umunhum is a landmark.

It is also a jewel.

During the Cold War, Umunhum was an Air Force Base. Its radar scanned the sea looking for incoming enemy craft. Satellites made the radar unnecessary, and the base closed in 1980. The Mid-Peninsula Regional Open Space District (MROSD) purchased it in 1986. But it has remained closed to the public, due to issues of access and toxic conditions left by the Air Force. It remains closed today.

But, after 25 years of waiting, things are starting to happen. The toxic cleanup of the site was finally funded, and is now complete. Much work remains … but the first obstacle to public access has been overcome.

And so, on an incredibly clear July day, MROSD invited a group of potential funding partners, including staff and volunteers from the Bay Area Ridge Trail for a tour of the mountain top. I was lucky enough to stow away in one of the vans and went along for the ride.


Question: What do these things have in common?

  • Big Sur
  • Mount Tamalpais in Marin County
  • Mission Peak
  • Mount Diablo
  • El Toro
  • The beaches of Seaside

You can see them all from the top of Mount Umunhum!

(Click on the pictures for larger versions.)

San Jose, Mt. Diablo, Mission Peak, Maguire Peaks

Morgan Hill, El Toro, Mt. Sizer

Mt. Tamalpais peeks out of the fog

Nearby Mt. Sombroso and the Woods Trail

Monterey Bay and Big Sur

Natural Resources

Even in July, there were flowers everywhere on Umunhum. Butterflies flitted everywhere. Bumblebees roamed from flower to flower. The mountain is literally buzzing with life.

Little Treasures

Lizard Looking for Lunch

Endangered Birds and Young

Man-Made Structures

While the views of nature from Umunhum are incredible, there are other sights to see. At least momentarily. Today the man-made structures of the Air Force Base remain. Stripped of their toxic paints and asbestos, many are reduced to shells. Now that the toxic danger has passed, most will soon be demolished, returning Umunhum to a more natural state.

The fate of the Cube itself is uncertain. Its seismic stability needs further study; the cost to preserve it would be high.

The Cube

The Tower

The Generator Building

What’s Next?

For now, except for special events, Umunhum is closed. Unsafe structures remain to be demolished; the road is twisty, narrow and dangerous; no trail reaches the peak. But the feedback that MROSD has heard from the public is clear: Get Us Up There!

If money can be found, the priorities will be to complete demolition of unsafe structures, complete a trail connection from the existing Barlow Road trail to the summit, and begin to prepare a parking area near the current Bald Mountain trailhead near Umunhum Road. With these complete, visitors could drive to the end of the existing road, park, and hike a mile or so up to the summit. They could take in the incredible views and return. There would be few amenities at the top, but the views would be enough reason to make the trip. Perhaps this could be ready in a few years … perhaps by 2014. In the meantime, options are still being considered – for van tours or other ways to let the public experience Umunhum.

Further out, again if funds are available, the road to the summit could be improved, making it possible to drive to the top. Interpretive features explaining the history of the site and its significance could be installed. A trail camp would let campers see the sunset views previously only available from the base commander’s window.

How you can help

Let your representatives in Congress know that funding for Mt. Umunhum is important to you!

If you have ideas for how to help – please contact the MROSD!

It’s amazing up there. I was truly lucky to get to see it. I want to go back – and see others get up there – NOW!

Thanks again to the wonderful people from MROSD and the Bay Area Ridge Trail who made my short visit possible! I won’t forget it!


  1. David

    Great photos and nice post. Thanks.

  2. Paul McWilliams

    Great pics! Can’t wait till it’s open!

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