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.
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