Look for a nice, easy hike with gorgeous views in North Cascades National Park? Here’s all you need to know about the Thunder Knob trail hike!

While I was visiting my friend, Caitlin, in Seattle, she wanted us to do a few hikes. After all, it was summer in Washington – what better time to get out of the city and into the mountains? While one day we did the Mount Fremont Lookout Trail in Mt. Rainier, another day we ventured further out to North Cascades with her mom.

It’s about 3-4 hours from Seattle and one of the least-visited national parks in the whole country. Seriously, according to states, it got about 30,000 visitors last year compared to Mt. Rainier’s 2.3 million and Olympic’s 2.4 million. If you have time, I think it’d be nice to stay somewhere in the park for a bit. Caitlin told me she and her mom used to come up every summer, and I can see why!

Quick North Cascades Hiking Tips

  • Getting There: We drove and parked at the Thunder Knob trailhead. It’s a very easy drive.
  • Make Sure to Bring: Thunder Knob trail is on the easier side, and we saw a girl hike in jeans and regular tennis shoes, so you don’t need to be as prepared as you would for more intense Washington trails. However, I really liked the support my Danner Mountain 600 boots gave and was happy to be in a normal workout clothes. Don’t forget your swimsuit to go swimming after unless you don’t mind getting your clothes wet!
  • When to Go: Summer is best as the weather is nicest and you can rely on roads and trails being clear. Too early or too late might mean snow and ice!
  • Fees: North Cascades is free to enter, and you don’t need any special passes to visit.
  • Length: 3.4 miles
  • Type of Trail: Out & Back
  • Time: I would say it took us maybe 1-2 hours with stops and photos.
  • Elevation Gain: 675 ft – it’s a lot of switchbacks which make it feel lot more gradual
  • AllTrails Map
Diablo Lake

About the North Cascades & Diablo Lake

So North Cascades National Park Complex is actually massive. It encompasses a northern unit, southern unit, Ross Lake National Recreation Area, and Lake Chelan National Recreation Area. Even outside the technical boundaries of the park, there are plenty of national forests and wilderness areas to explore.

Its name comes from the North Cascades Range, which spans through both Washington and British Columbia in Canada, and was officially established as part of the NPS in 1968. Back in the day some claimed the scenery was more beautiful than Switzerland, and looking at general pictures it reminded me a bit of the Lyngen Alps in northern Norway.

If you look on a map, Diablo Lake and Thunder Knob trail look like a tiny dot right in the center of the park. That’s how big this place is compared to what we managed to see in a day. The lake is the result of the Diablo Dam and it gets its turquoise hue from the nearby glaciers. It’s an icy swim but so refreshing!

How to Spend a Day Hiking Thunder Knob Trail

Driving to Northern Cascades

Start Early

I will say despite North Cascades being one of the least visited parks, the parking at the trailhead is limited and fills up quickly. We meant to leave Seattle by 8 AM but didn’t get on the road until closer to 9/9:30 AM, and by the time we got there the lot was full. We were super lucky that someone was pulling out right as we arrived, or else I’m not sure where we would’ve parked. Diablo Lake is a pretty area to relax, so people also just come to float on the water or swim, hence why it’s a little busier than if it was just a trailhead.

For best chances, leave around 7:00 AM and no later than 8:00 AM!

Stop for breakfast at Calico Cupboard

Along the way we stopped off at Calico Cupboard’s Mount Vernon location for breakfast and to pick up some baked goods for the ride back. Calico is one of the first bakeries in Skagit Valley to make their food bot sustainably and from scratch, and has been in operation since the 1980s. It’s SO worth the stop if you’re near any of their locations.

Parking at Thunderknob Trailhead

Park at the Thunder Knob Trailhead

This is the parking lot for the trailhead – you can see why things fill up quickly! If you just plug in Thunder Knob Trailhead into Google Maps, it’ll take you here, but know the lot is actually along the highway. Colonial Creek North Campground is also located here if you want to stay overnight; just book on recreation.gov.

Campground entrance

Walk through the campground to find the entrance

Just walk through the campground and you’ll quickly see a sign to start the trail. There are two separate vault toilet areas for anyone who needs to go.

Rocky bit over river and bridge

The beginning of the trail is through the forest area. It’s a little rocky, but otherwise pretty easy. I remember being struck by how different the nature here was to that in Mt. Rainier. This is more alpine forest as you can see above.

Dirt path portion of Thunder Knob Trail

Chang to a dirt path for the rest of the route

Once you start to climb, the path turns to a nice, smooth dirt path. Honestly, if you’re into trail running, you could easily run this path without worrying about rocks. I really liked all the switchbacks we had and it just made the whole thing feel a lot easier than most hikes I’ve been on.

Two views of Diablo Lake

Before we knew it we were at the viewpoints for Diablo Lake! There are two different viewpoints to take in the view, so take your time enjoying them before following the trail back down.

Swimming lake by trailhead

Go swimming in the lake afterwards

If you’ve followed my recommended leave time, you should finish by early afternoon. Spend a few hours and enjoy the lake! I saw someone have a raft to just float out on, and I personally went for a swim. The water is icy but felt SO good after sweating it out in the sun. We didn’t have suits, so we just jumped in in our workout clothes.

Seriously pack a lunch, some lounge chairs, a raft to float on, and a good book to while away the afternoon.

Pop over to the Diablo Lake Vista Point

Before you head home, be sure to drive out to Diablo Lake Vista Point for even more beautiful views. I mean how often do you get to see a body of water this shade of blue? Take it all in!

And there you have it – everything you need to know for hiking Thunder Knob Trail and enjoying Diablo Lake! Such a small but stunning part of North Cascades National Park.

For more travel in the Pacific Northwest:


How to hike the Thunder Knob trail in Northern Cascades National Park, Washington, USA

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