Not really a secret, but little known entrance to the trails at Montalvo. There is legal parking nearby but not at the trailhead itself.
The cache is an ammo can hidden just a short distance in from the trailhead.
This would be a 1 star hide IF there was any chance of getting a signal in the area. I got the coordinates above on my 1st try but could not test them because I couldn't get any satellites after that. If you have problems, try starting at N37º 14.635 W122º 02.123. Head down the trail about 18 paces, then go south. The cache is at the "north end" (you'll know it when you see it).
There was a little poison oak at the hide, but it was easily avoided.
6-6-04: I updated the coordinates to match the ones used by Kablooey. I still can't get enough signal there, but we'll try these for a while and see if they work out!
8-30-04: tweaked the coordinates just a bit more after taking 2 more readings today and think they are pretty good now.