I did this as a day hike - roughly 2.5 miles out for a 5 mile total - and it was truly lovely. The old growth forest is beautiful and the trail is so easily navigated (especially up to the Thunder Creek bridge crossing) that hikers of any age and experience will be able to enjoy it. The trail has a gentle incline upon crossing the bridge so much so that I barely noticed the steady rise until the creek was rushing far below me. On the 2.5 miles out, I passed the Thunder and Neve campgrounds, crossed another small creek, and decided to turn around at a bridge crossing a small waterfall. My only annoyance: the bugs were out in full force and even though I was wearing bug spray, they were still flying around me, so definitely bring spray.

We started this in-and-out backpacking trip at Colonial Creek Campground and camped the next three nights in Junction, Cosho, and then McAllister, consecutively. Trails and campsites were in excellent condition, despite rain and mud on the third/fourth days.

The first day was about 10-11 miles of hiking from the trailhead up to Junction Camp. The first 8 of that was slow rolling hills along Thunder Creek to where it joins Fisher Creek at Tricouni Camp. Immediately before Tricouni we encountered trail crews who warned us that the next two miles (Tricouni to Junction) have no water access and are one "annoying hill". As promised, we didn't have access to the Fisher Creek below, but we were able to capture photos of it's substantial waterfalls and of the mountains overhead.

Junction camp hosts incredible views and is a convenient stop for access to both the Thunder and Fisher Creek trails. Climbing up from Tricouni is challenging, but completely worth it for the campsite upgrade. We encountered two other parties staying in Junction for day hikes up each creek.

From Junction on the second day we pursued one short day hike (without packs) down to the mining cabins in the meadows. The descent (and subsequent ascent) was very steep, and we felt the impact for the remainder of our hike to Cosho later that day. The short side-course was worth it, however, to see these fascinating artifacts of the Cascades' mineral history. We had the fortune to coincide with a parks maintenance crew who were busy restoring these structures, using local timber and era-appropriate techniques. They took a break to give us a tour and tell us about the history of the planned but never built town at Skagit Queen, up Thunder Creek.

After ascending out of the meadow we collected packs and proceeded to Cosho Camp up Fisher Creek. The next few miles of the Fisher Creek Trail (heading East from Junction) were harder than expected. We could see some remnants of an older trail which closely followed the creek, but the trail today diverges from the gradual creek slope to frequently rise and fall in altitude. Water crossings later in the trail are well-maintained, but are usually simple beam-and-handrail bridges which could be hazardous in wet conditions. Fortunately we crossed each time before the rain started and encountered no trouble.

Cosho Camp is empty and very convenient. Campsites have excellent creek access and plenty of open space, but the forest canopy made mountain views harder to come by.

The third day of hiking we turned around to make our way back towards the trailhead. Weather forecasts predicted rain this day and we picked up the pace to get to McAllister Camp. We arrived with just enough time to pitch tents and keep dry.

McAllister camp is beautifully prepared, with an easy-to-use bear hang wire and tent platforms, however water requires a longer walk.

If we were to do this trail again, we would stay multiple nights in Junction and do long scenic day hikes down each creek trail. Junction is by far the most scenic campsite in this report.

Lovely hike. Up and down trail, soft footing and creek crossings. The trail was quiet few people beautiful old growth trees, give them a hug they need it! The sound of the roaring creek, more like a river, is always present, expect for a moment when there is a hill between you and the river. This was a great first backpack trip for the season to get your legs and lungs ready for some hard stuff later in the season. 

Gorgeous day out in the Diablo Lake area! Temps were in the low 70's by the time we hiked out at 3:30 p.m. Thunder Creek trail is in excellent condition, well-signed, no blowdowns. There are a few short, minor stream crossings, easy to rock hop or even walk straight through, as the water is so shallow. We ran into two 12-person backpacking groups in the morning (hiking out), one from a school and the other a father/son/men/boys-without-dads-group, which was cool. The trail is an excellent place for backpackers who want something fairly mellow or who are new to backpacking. We hiked to McAllister camp and back (actually, hiked to the horse camp), 6 miles one way. You only gain 700 feet, according to Green Trails, but it does go up and down a fair amount, so it's probably at least 800-850.

We arrived at the Colonial Creek Campground, where the TH is, at 9:30 a.m. and hiked to the horse camp--not that we had any equine friends with us. Heads up re: McAllister hikers' camp: some Park workers were cutting trees (blowdowns) around the camp sites and asked us to stay out of the campground today. Seems like they will have wrapped it up by the end of today. . .? The Group Camp, about 100 feet ahead, and the horse camp were both open. Horse camp looked pretty nice--no horse flies yet! One of the workers told us about a sweet spot in the horse camp area--hike down through the camp, and follow a narrow trail to the left, which takes you to the edge of a bluff. (Don't get too close, it's eroding!). This bluff overlooks Thunder Creek, far below, as it bends through the surrounding slopes (see pic). After having lunch here, we turned round.

Features: This hike gives you lovely "creek" (seemed more like a river) views, both during the first 1.5 miles, as well as once you near McAllister, 5+ miles in. It also has some snow-covered peak views along the way. Thunder Creek trail is resplendent with old growth Doug Firs and cedars. Awesome. It was quiet today--just the two big groups and a handful of Park workers. Flora: bunchberries, Herb Robert, spring beauties. Fauna: 2 chipmunks,one deer, a large bullfrog, and the bug that flew down Edelman's throat as we hiked. A couple mosquitos, but I was surprised there were hardly any. Great first summer foray into the mountains. 12 miles RT. Happy and safe hiking, All!

What a wonderful, rambling trail!  I arrived to the trailhead in the back of the campground at 6:30am to start my run/hike adventure, 1 other car parked in that area.  I am loving a trailhead with running water in a real bathroom! 😂

Trail is in great shape!  Work has obviously been done already this season rebuilding tread, logging, and clearing debris- thank you trail crews!!!

I sped along until just beyond the turn off for 4th of July Pass when my progress was slowed by a doe with 2 fawns on the trail, after several enjoyable minutes they continued into the brush and I pushed on past Neve campsites and on to McAllister.  The new McAllister campsites look great, complete with bearpole and separate cooking/tenting areas.  

The creek crossing just past McAllister is now rock-hoppable and numerous smaller crossings can also be crossed with dry feet.  Continuing on to the large bridge at Tricouni camp I took a snack break and relaxed on the sand along the creek before starting the climb up to Junction campsites.  

If you venture out this far there are great views from the Junction campsites, even if you're not camping take the 200ft detour to enjoy the views!  the trail remains buried in the trees so don't skip this and miss out!

From Here I was torn on whether to continue along Thunder Creek or to explore Fisher Creek, so I did a little bit of both!  Junction campsites is pretty obviously where the trail maintenance has reached as both trails began to have winter debris/branches on them.  I kicked/threw the most egregious out of the way.  I continued down along Thunder Creek trail about 2 miles as it dropped back down to the creek before turning around and kicking myself for doing 2 miles of downhill...that I now had to go back up.  Hiking back up to Junction camp I took a breather hanging out in the sunshine before exploring up Fisher Creek trail.  almost immediately there are trees down and things are brushier than on Thunder Creek, I continued about a mile along before finally giving in to my complaining calves and turning around.

Return journey was relatively uneventful, saw 2 more deer, and I saw some people!  I passed 5-6 groups of dayhikers between trailhead and McAllister and probably an equal number of backpackers. returning to the trailhead about 4pm parking was now about 2/3rds full.