From the late 1800s to the early 1990s, as many as 900 miners at a time labored to remove nearly 4 million tons of coal—“black diamonds”—from the ground in what is now Black Diamond Mines Regional Preserve near Antioch in Contra Costa County.
As interesting for its human history and artifacts (mine shafts, cemeteries, crumbled buildings) as for its 65 miles of pet-friendly trails, this 5,375-acre open-space oasis, part of the East Bay Regional Park District, is an off-the-beaten-track, mostly off-leash, find for DogTrekkers.
The hilly, oak-studded landscape reminiscent of the Sierra foothills melds into oak chaparral and evergreen forest to keep things interesting for you and Bella.
The best hiking is in winter, when you won’t mind the lack of shade on the 6.1-mile Somersville-Nortonville-Black Diamond loop trail topping out on a hilltop with views overlooking the Oakland and Berkeley hills and the blue bay beyond.
You and your four-legged sidekick will have to start out connected by a leash, but once 200 feet clear of parking lots, trail heads, staging areas, campgrounds, visitor centers and other developed areas, you can unclip and let her romp unencumbered in the emerald landscape.
Just make sure she's "under control," which means staying within eyeball distance, coming when called and steering clear of equestrians, wildlife and livestock.
Climb high for the best views, and expect a good wildflower show in March.