Thirty miles south of Seattle, the town of Black Diamond has traded coal dust for lake water. Founded in the late 1800s by a California mining company, it once ran one of the largest coal operations on the West Coast, with dozens of shafts in the Cascade foothills. These days around 7,000 people live there, up from roughly 4,700 in 2020, making it the second-fastest growing city in Washington according to World Population Review. The growth is driven largely by the Ten Trails master-planned community, which welcomed its first residents in 2018, and city planners expect the population to hit 12,000 by 2040.
For travellers, that boom matters less than what surrounds it. The Black Diamond Historical Society calls it a "Town of Many Lakes", and the water access is genuinely good. Lake Sawyer, in the northwest corner of town, is one of King County's largest natural lakes at 286 acres — private homes ring most of it, but there's a public boat launch off the paid lot on SE 296th Street. Lake 12 covers about 41 acres with a boat ramp on its southern shore. Ginder Lake, which sits over an old mine site, is private and off-limits.
Hikers get their share too. Lake Sawyer Regional Park on the south bank is the trailhead for over a dozen miles of routes, including the Lake Sawyer Trail — a 2-mile-plus AllTrails favourite that follows the shoreline and a feeding creek. Bring a map: reviewers note that public access points are easy to miss and some paths edge onto private land.
The state parks nearby round things out. Nolte State Park, a ten-minute drive away, wraps 117 acres around Deep Lake by the Green River Gorge — paddling and non-motorised boating on calm water, a sandy beach, picnic spots and an easy lakeside loop. Kanaskat-Palmer State Park, also close by, is a 320-acre riverside retreat along the Green River with secluded, woodsy campsites and rapids that draw experienced rafters depending on the season. A few miles southwest, Flaming Geyser State Park covers 480 acres and takes its name from a methane seep accidentally ignited by a coal miner in the early 1900s — a nicely odd bit of history attached to a solid trail network.
Who's this for? Not a destination weekend on its own — lodging in town is thin — but Black Diamond works well as a day trip from Seattle, roughly half an hour from downtown and Seattle-Tacoma International Airport. It suits outdoorsy travellers based in the city who want lakes, quiet trails and low-key state parks without fighting I-90 crowds, and it pairs naturally with a stop in the Green River Gorge area.
