This trail pays out some serious rewards for being both short, and relatively low-elevation. It begins in the Colonial Creek campground, crosses a stream, winds through old-growth forest, and then gently climbs into rocky forest and mountain views, a tiny alpine pond, and, at the end, a breathtaking view of the green-blue waters of Lake Diablo and a 360-degree panorama of the Cascades.

Only con: Colonial Creek was completely overflowing on the day of our visit, and had fully washed out the first 200-300 feet of the trail. In some places, the water was about half a foot deep, and I barely managed to keep my feet dry in sturdy, tall, waterproof hiking boots, and my friend, who didn't have waterproof shoes, ended up hiking in wet shoes. We almost turned back, but are so glad we didn't. Still, come prepared either to get wet, or wear tall waterproof boots!

Oh, also, with the exception of one other person, we were the only people wearing masks on the trail. It wasn't crowded, so it wasn't too big of a deal -- we just tried to keep a social distance -- but please brings masks with you while hiking! We're still in a pandemic, and probably will be for a while.

The hike started out on a sunny afternoon of Farther's day, June 21st. The weather was getting better as the day progresses, and warmer too. There is only a small portion of the trail is shaded. TH is by SR 20, not far from the Diablo Overlook. It is a short hike with a few switchbacks and some elevation gain, there are also some benches all over the trail. I also saw some small children hiking with their parents. At the top, there are plenty of places for photo ops and sitting area. The lake is hiding behind the trees, it is the greenest lake that I have ever seen. The view is fantastic.   

We camped at Colonial Creek for three nights over Father's Day and took advantage of the two hikes available at either end of the campground. It turned out to be very convenient to not have to drive to either trailhead because the parking areas fill up quickly! 

The trailhead for Thunder Knob is located at the north end of the campground and is well signed. The first part of the trail is partially under water and it is evident that the creek has flooded several campsites but there is a bridge over the worst of it. After you cross the bridge, the trail is easily found and is moderately graded with several switchbacks to the main viewpoint at the summit. There are also benches and many viewpoints along the way. The trail is wide and in good shape at this time. We started our hike around 9:30 on a cloudy Saturday morning and there were not too many other hikers out. Those that were out hiking were respectful of physical distancing measures. 

The trail for Thunder Creek is located at the south end of the campground. There is a small day use parking area near the trailhead and additional parking available in the large parking area in the middle of the campground. We decided to hike to the Neve Camp about 3 miles in and once there we found a spot for lunch with a viewpoint looking over Thunder Creek. The trail is mostly flat but there are some areas where the trail is narrow that could use some brushing and a couple of water crossings near the Neve Camp. The water crossings are not difficult but will require you to stop and consider your path if you don't want wet shoes or boots. We encountered more traffic on this trail but most people were respectful of physical distancing. 

Parking lot was full, we had to circle back in a few mins to get a spot. Easy hike. Trail in good condition. We took a picnic backpack with us and had a small picnic at the overlook. Beautiful views at the end!!!! 
Really good easy short hike for people looking for great views.

Hiked 16Jun2020 and started out ~07:00 from Colonial Creek South campground (where we camped last night). The Trailhead is in the Colonial Creek North campground. It was very easy to follow the trail: passed a few small streams, headed into the forest, ~1 mile in .. reached the first Overlook of the mountains, continued going for another ~1 mile to reach the Lake Overlook - lovely views of the Lake and surroundings. imho - it’s a relatively easy-mild incline the way up and not too difficult or tedious - esp cos the trail seems well-maintained. I only encountered 2 hikers on the trail which is kinda nice too :P 

Happy Trails Everyone!