I have been to here twice. The first time everything is OK, and I have taken a number of pictures. The second time, I was trying to challenge myself a little, and ran into huge trouble.
The trail is known as "Woods Trail." If you come from CA 85, exit #8 at Camden Avenue. Stay in the left lanes, and at the end of the ramp, turn left onto Camden. Drive 1.7 miles, then turn right onto Hicks Road. Drive 6 miles, at a stop sign, turn right onto Mount Umunhum Road, and the trailhead's parking lot is right on you right. You will see the sign below.

Woods trail features with its name: a lot of trees covered the trail so that even in a sunny day, you still have a lot of shades. The trail is 2.7 miles one-way, and moderately easy.
Hiking in bayarea, you can see a lot of power towers, which I like very much. In Sierra Azul, you can find some very unique ones.

Power lines pass the valley with a huge span, and looked very elegant. This picture was take on the other side of the valley.

On you way, scenes change from time to time, sometimes you can see low clouds on other mountains.


You will also see the peak of Mt. Umunhum with some concrete box on the top. Today, when I looked at this picture, I have a very special feeling :−)

Woods Trail ends with a fork to three different directions: going back, Alma bridge road and Barlow Road.

I took the Barlow Road which started to be pretty steep. After less than a mile ascendant, I got the top of the trail, with the peak of Umunhum right in front of you. On the official map, that area is closed to public. My trouble started for not consulting the map in advance. :-P

Started from (1), I went off the trail and started to climb to the peak of Mt. Umunhum. This time, I was fully convinced by the Chinese saying: "Mountains right in front of your eyes may take your horse's life." The concrete building looked so close to me, but actually it was 1000 feet higher than where I stood!
The terrain was very tough, with soft soil sliding all the time and woods all around. Many tree branches looked very thick, but whenever you tried to grasp them, they would fall. Many rocks were so weathered that they could not hold my weight. Towards the end, I had to move on some huge rocks, steep cliff was right on my side. When I got to the top of the mountain, there were fences around the building with sign saying "Hazard zone, keep out!"
Not a single person was there. I didn't want to get into troubles so I started to hike down. At the beginning, I tried my best to follow the same path I came, but soon found it not possible. With all the trees around, I could hardly know the direction.
I ended up following a creek and went down until I got to point (2), where I started to see water in the creek. Had I been a little more experienced, I would have followed the creek further. However, for no reason, I felt that was not the right way to go. So I went off the creek and moved toward point (3), where I realized I was totally lost!
It was so lucky that my cell phone still had signal there! So I called my wife and 911. Time was 5:30PM and the sun started to set. I soon got phone calls from the rangers saying that a number of people had been out to look for me. But with limited information and ways to communicate, they had trouble to locate where I was.
Soon, it turned fully dark all around. My wife sent me a message:"There are mnt lions in that area so get some stick in your hand. ..." I wasn't able to find a good stick, so I started to collect some rocks. It was not as cold as I expected, but I did not have any idea how I was going to stay there for a whole night. I did have a little water and food in my backpack, but my cell phone's battery had only one bar left.
Rangers used sirens and lights when they drove on the trails, they called me to see if they are getting closer or not. Finally, they stopped at a place where I can clearly see the lights on their trucks. "Help! Help! Help!" I guess I said more "help" than I did in my life so far, I even tried to wave my cell phone with light on. (Later on, after I was rescued, I was told that they could not see it.) The rangers started to climb up along the creek, I could even see their flashlights! I made my way towards them, shouting loudly to let them know where I was, and finally, I was rescued.
To cut long story shorter, I was rescued at around 8:15PM. The ranger who found me gave me a ride to the trailhead. His name is John. On the way, he said to me: "Most time hikers get lost when they go off the trail; most time they are injured when they go off the trail; so, keep this in mind: stay on the trail when hiking!"