We stayed at Colonial Creek South Campground, just across the highway from Thunder Knob. It was a 10-minute walk from our campsite to the trailhead. We started hiking around 6:00pm and had the trail pretty much to ourselves. Most of the trail is in the forest, but there are a few sunny spots that can get a bit toasty.

Once we reached Thunder Knob itself, we stopped at each of the rest areas to check out the views. It seems that the trees have grown in quite a bit, so many of the vistas are partially or completely blocked. The first viewpoint is the best, with a great panorama of Lake Diablo, the power plant, and the surrounding mountains.

This is a fun trail to check out if you're camping in the Colonial Creek area. It would also make a great rest stop if you're traveling through the park on Highway 20.

Great little stop at Diablo Lake. Beautiful views and many benches that make for a perfect family hike.

I was pleasantly surprised at this little hike. My husband and I have always wanted to check it out and I am glad we finally did. The hike is an easy one but parking was kind of nerve racking. The trail is well kept and the kids thought the little benches along the way were awesome! Although you can hear the highway in some parts there are plenty of spots where all you can hear are the chipmunks and birds. My kids were excited to find a couple of newts along the way too. Perfect hike for kids.

Went on this hike over the 4th of July weekend. There were a few groups, but the trail wasn't crowded at all. Parking was plentiful, considering the campground was full. We were able to find a spot for the F150 just by looking around a bit at the two small lots near the TH. Follow the signs through the campground that will point you directly to the TH. The trail is in great condition, although I see markings where someone is planning a little trail repair in the switchbacks. Please, don't take shortcuts, it doesn't save that much time and it causes trail erosion and added work for those that volunteer their time to keep these trails safe and in good condition for us. Enjoy your hike, there are views along the way as well as a spectacular view of the lake and mountains at the top.