Note: The bridge over Thunder Creek located 14 miles up the Thunder Creek Trail near Skagit Queen Camp in North Cascades National Park has been replaced.
Hike one of the longest valley trails in Washington, nearly all in magnificent old-growth. This is real North Cascades wilderness, tucked into one of the largest roadless areas in the 48 states. This can be a multi-day backpacking trip up the tumbling, boisterous, river-like Thunder Creek from the Colonial Creek Campground to just beyond its headwaters at Park Creek Pass.
The round trip mileage from the Thunder Creek trailhead to Park Creek Pass is about 40 miles, but what is not obvious until you are there is that 38 or so of those miles are in the forest. You don't break out into the open until the very end, above the Thunder Basin hiker camp.
Even then the views are good but not expansive — you can see the shoulder of Logan and pieces of Buckner, as well as several lesser peaks. Still, the old-growth is impressive, and walking along roaring Thunder Creek is oddly peaceful.
The first eight miles are relatively low-key, with about 1000 feet of elevation gain, mostly on excellent trail. Go by four National Park Service camps and the junction with the trail to Fourth of July Pass. Enjoy the big trees, and the equally impressive flow of Thunder Creek.
For six miles, the trail is in a National Recreation Area, which means dogs are allowed — many day hikers bring them. But past mile six you enter the National Park, and pups have to turn around. For hikers, after the fourth camp, Tricouni, the trail climbs another 1000 feet in two miles along Fisher Creek.
Reach Junction Camp after a total of ten miles from the trailhead. The trail to Fisher Basin and Easy Pass takes off from here. In Junction Camp you get your first real views, of the still-enormous Boston Glacier, through a gap in the trees.
Note that a 2022 fire burned timber on the west side of Thunder Creek; blackened trees may be visible at times.
The trail proceeds to lose nearly all the elevation you just gained as it returns to Thunder Creek. The point of this up-and-down excursion is to avoid a huge swampy area along the creek.
Begin climbing again, to Skagit Queen camp, then on switchbacks into higher country. Some signs of mining, which lasted into the 1950s, are apparent through this stretch. Small meadows appear around 4000 feet, though big trees still dominate. If you hike the upper portion in the morning, expect soaked legs from meadows wet with morning dew. Just before the Thunder Basin stock camp, ford Thunder Creek, much diminished but still knee deep with a strong current.
A sign at the stock camp indicates it is 0.75 mile to the hiker camp, but it may feel like much more. The hiker camp, in meadows and small trees next to the creek, is likely to be quite buggy. Climb the trail another 1000 feet or so to Park Creek Pass, elevation 6000 feet, getting the best views of the hike. There are scattered larch trees
Once you top out at Park Creek Pass everything changes. Mountains, meadows, and scrambling opportunities abound. This is a place to stay awhile. Camping isn't allowed in the pass, but there are good camps on either side. So few people ever make it this far in that you will almost certainly have this wonderland to yourself.
You can make a long one-way hike from the pass by first descending to the Stehekin River valley, then exiting via Cascade Pass or following the valley down to Stehekin. Both routes require prior transportation arrangements.
A note about the elevation gain
Diablo Lake is about 1000 feet, and Park Creek Pass is 6000 feet, so there is a net gain of 5000 feet along this trail. However there is a bonus climb of 1000 feet to Junction Camp both coming and going, so the total elevation gain for the roundtrip is more like 7000 feet. The trail is never terribly steep, but be prepared for some climbing!