Lake Diablo Is a Hidden Gem in Washington

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Diablo Lake in Washington shines bright turquoise in the sun, surrounded by mountains.

Here’s a riddle for you: What’s cold and bright green surrounded by old-growth forest 1,200 feet above sea level? If you answered “Lake Diablo,” you’ve likely spent some quality time in the Pacific Northwest. If not, you may want to learn more about this magical place in the mountains.

There’s something strange and captivating about Lake Diablo that makes it stand out from other memorable features in this gorgeous region. What’s unique about Lake Diablo? Let’s find out!

Where Is Lake Diablo?

The glacier-fed Lake Diablo, inside the Ross Lake National Recreation Area, is so far north it’s almost in Canada. The 800-acre reservoir is in northern Washington State near its shared boundary with British Columbia.

It’s one of many attractions at North Cascades National Park, which borders Mt. Baker-Snoqualmie National Forest. Sometimes called the American Alps, this area is about 125 miles northeast of Seattle and 90 miles east of Bellingham.

Why Is Lake Diablo So Green?

The first thing you’ll notice about Lake Diablo is its spectacularly vibrant hue. Some say it’s green, while others call it bright blue or turquoise. Don’t worry, though. This unusual and intense coloration is perfectly natural.

It comes from minerals in the rocks that make the mountains. Glaciers rub against them constantly, gradually grinding them into a fine powder. These particles washed downstream into the lake are sometimes called glacial flour.

Aerial view of a road curving along the green waters of Diablo Lake in contrast to redish orange trees.

Can You Swim in Lake Diablo?

One of the many questions that visitors to Lake Diablo ask is whether it’s safe to swim there. Well, yes and no. You don’t have to worry about the green color rubbing off on you, but hypothermia is a real concern. Swimming is allowed here, but be prepared for a chilling experience.

After all, the water is from melted glaciers, and it’s often very windy, too. We recommend dipping a toe in first, or a foot or two, to test the waters. The shallower areas along the shores of the campgrounds are probably your best bets because they are probably a touch warmer.

Traveler’s Tip: Looking to take a swim on your next vacation? Dive into the fresh water of the Great Lakes in these amazing small towns in Michigan.

Things to Do at Lake Diablo

What can you do at Lake Diablo besides gaze at this almost mesmerizing and somewhat mysterious pool of green? There’s quite a lot, actually. We’ll walk you through some of the most popular activities in and around the reservoir.

Visiting North Cascades NPS || Diablo Lake

Go Hiking

Take the out-and-back 7.6-mile Diablo Lake Trail and climb the slopes of Sourdough Mountain. You’ll see stunning views of the lake as well as Jack Mountain and other impressive peaks.

Along the way, you’ll encounter Gorge Creek Falls with its 700-foot cascade. The hike has an overall elevation gain of around 1,400 feet and includes a 600-foot descent to the Ross Dam area.

A quick and easy alternative is the Happy Creek Forest Walk, a 0.3-mile loop (mostly boardwalk) through a shaded forest.

Book a Boat Tour

Another way to see the lake up close is by boat. Guided educational boat tours run twice a day during the summer season, which starts in July.

The vessel, called the Alice Ross IV, was designed especially for Lake Diablo excursions. It has a glass-enclosed cabin with climate control and comfortable seating. Passengers can also enjoy the tour from the rear deck seating area.

Each tour includes a discussion on the history and importance of the Skagit River Hydroelectric Project, which created Lake Diablo and two other lakes.

The Skagit River Hydroelectric Project generates sustainable power for the city of Seattle.

Go Camping

North Cascades National Park has six different established campgrounds. Two of them have fishing piers and boat launches with direct access to Lake Diablo.

Colonial Creek North has 41 sites for RVs and tents, and Colonial Creek South has 10 walk-in tent sites. Amenities are minimal — just potable water and toilets but no electricity, sewer, or dump station. You can also boat in for remote backcountry camping on islands on the lake.

Camping is limited to 14 days during the peak season, which is July 1 through Labor Day. You can camp up to 30 days the rest of the year, and it’s free.

Stay Overnight at the North Cascades Environmental Learning Center

To learn more about this amazing area, visit the Environmental Learning Center. This is where the biologists and botanists do their research, but the public can also participate in hands-on experiences. It’s right on the lake, and there’s a dock you can use to drift off on floating adventures.

The center has a dining hall, amphitheater, outdoor shelters and trails, and overnight lodging. Through a program called Base Camp, you can spend the night here. They serve three locally sourced organic meals a day and guide you through educational activities throughout the park.

A boardwalk heading up a small waterfall in the forest.

Go Fishing

On Lake Diablo, anglers cast a line for several kinds of fish, including brook trout, bull trout, and coastal cutthroat. In addition, the Skagit River is a productive spawning habitat for all five native species of salmon.

You can launch your own boat or fish from a public pier. Keep in mind that you’ll need a Washington fishing license beforehand. They aren’t available for purchase on site.

Take a Scenic Drive

Actually, any drive you take in this area is a scenic one. The only road through North Cascades National Park is State Route 20. Also called North Cascades Highway, it doubles as a 30-mile scenic drive.

It starts at the visitor center and offers overlook areas with interpretive signage every few miles. The Lake Diablo Overlook is one of the most popular stopping points, along with the falls and Ross Lake.

What Can You See at Diablo Lake?

The prominent Colonial Peak, rising over 6,500 ft over the lake, will catch your eye. (Like the creek, it takes its name from an old mining company.)

Bald eagles are so prevalent in this area at certain times of the year that there’s an annual eagle-watching festival nearby. They’re just one of around 200 species of birds you may spot. In the spring, tiny hummingbirds are especially drawn to particular wildflowers like salmonberry and Indian plum.

On the shores of the lakes, a forest floor of lush ferns thrives among poplar, maple, and alder trees. Lake Diablo’s furry population includes wolverines, gray wolves, Canada lynx, and Columbia black-tailed deer.

Mountains of the North Cascades covered in snow tower above the clear waters of Diablo Lake.

Lake Diablo Is a Hidden Gem in Washington 

That brilliant shade of green lures visitors to Lake Diablo in Washington State, and they’re in for a once-in-a-lifetime experience. Once there, however, they discover many other places worth exploring, including its neighboring waterways.

Like Lake Diablo, Ross Lake and Gorge Lake were built to help provide electricity to the city of Seattle. The Skagit River, which feeds them, remains pristine enough to be designated as a National Wild and Scenic River. 

Another great reason to visit Lake Diablo and its surrounding area is that it’s not overcrowded. In fact, North Cascades is one of the least-visited national parks, with fewer than 18,000 visitors a year. Along with the breathtaking beauty you’ll witness, that truly makes this place a hidden gem. 

Will you put Lake Diablo on your bucket list?

1 comment
  1. Thank you for the great idea of a beautiful place to visit.
    I’ve been over the North Cascade Highway many times and always find myself amazed at its beauty. When conditions are wet, watch for falling rocks along the south edge of the highway. Take binoculars and a camera. Rumor has it that there is a possibility of grizzly bears in the remotest areas, that have worked their way down from B.C. I say “rumors” as I don’t know for sure and only the game department feels it is capable of making such an identification. Bear spray would be advisable on any back country hiking, and a firearm might be a good backup in capable hands. Obviously, cougars also frequent the North Cascades.

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