Washington's Former Coal Mining Town Is A Fast-Growing City Outside Seattle With Lakes And Nearby State Parks

Lumber may have dominated Washington's early economy, but coal also played a big role in fueling the Evergreen State's development. As far as coal towns go, Black Diamond — fittingly located in King County — was one heck of a powerhouse back in its heyday. Tucked into the foothills of the Cascade Mountains just outside of Seattle, Black Diamond had dozens of mines. In fact, it was home to one of the largest mining operations on the entire West Coast. The rural hub was founded by a decamping California mining company in the late 1800s, with the earliest residents consisting mostly of miners and their families.

Today, around 7,000 people live in the area, per the U.S. Census Bureau. This is a big jump from 2020, when nearly 4,700 folks called the place home. Black Diamond was named the second-fastest growing city in all of Washington in 2026 by World Population Review, trumped only by Ridgefield, north of Portland. The Ten Trails master-planned development largely drove this rapid expansion after welcoming its first residents in 2018. The community is showing no signs of slowing down any time soon, with a projected population of 12,000 by 2040, according to official planning documents. 

Black Diamond is located only about 30 miles from downtown Seattle, making it an easy choice for a day trip. It's about the same distance from Seattle-Tacoma International Airport (SEA) if you're visiting from out of town, though lodging in Black Diamond is pretty limited. The burgeoning suburb is a boon for nature adventures, fringed by forests and protected wilderness areas. There are several scenic lakes within reach, along with a string of state parks, giving you plenty of options for soaking up the great outdoors.

Dubbed a "Town of Many Lakes" by the Black Diamond Historical Society, the former coal mining town seems to have traded its dusty shafts for tree-lined waters. Take Ginder Lake on the outskirts of city limits, which once served as the site of an underground mine. The little lake sits on private property, so it's not open to the public, but you can find several other places to make a splash around town.

The nearby Lake Number Twelve, or Lake 12, spans about 41 surface acres, with a boat ramp on the southern shore. Lake Sawyer, up in the northwest corner of town, is a bit more popular. It may not be one of Washington's top deepest lakes, but it's definitely one of the largest natural bodies of water in King County at 286 surface acres. Lake Sawyer is surrounded by private property, but there is a public boat launch off the paid parking lot on SE 296th Street. 

If you'd rather stretch your legs, more than a dozen miles of hiking trails weave out from Lake Sawyer Regional Park on the south bank. The Lake Sawyer Trail is one of the top-rated routes on AllTrails, running for just over 2 miles along the expanse and a winding creek that feeds into the lake. Just be sure to look for posted signage to avoid wandering onto private land. As one visitor warned in a Google review, you may want to have a trail map handy, as the public trail access points can be tricky to find. "Otherwise, this place is beautiful," the hiker added. "Could explore for a full day, huge network of trails!"

More lake fun can be found at Nolte State Park, just a 10-minute drive from Black Diamond. The compact recreation area stretches for 117 acres along the tree-lined Deep Lake by the Green River Gorge, a beautiful canyon carved by its winding namesake waterway. You can spend some time paddling the peaceful waters or take your boat out for a spin, so long as it's non-motorized. If it's not too nippy, lounge on the sandy beach, or fire up the grill for a lakeside picnic before rounding out the day with a stroll. "There are so many trails to walk all around the lake," one online reviewer wrote. "It's a beautiful place."

Kanaskat-Palmer State Park is about the same distance away from town. Standing right along the Green River, this 320-acre wilderness retreat is favored for its secluded woodsy campsites, so be sure to bring all the gear you need for a camping adventure. Seasoned rafters and paddlers can tackle the rushing rapids, which could rival some of the best rivers to go whitewater rafting, depending on the time of year. Flaming Geyser State Park is just downstream, just a few miles southwest of Black Diamond. The 480-acre recreation area was named for its once fiery methane gas seep, which was accidentally sparked by a miner drilling for coal in the early 1900s. "Great trails, history and just a nice place," one visitor shared.