Wolf Den Run State Park is Maryland's first and currently only park that caters to four-wheeling. There are three designated areas, each with numerous trails. A permit is required. The trails are open year-round except for deer firearms season, the two weeks beginning the first Saturday after Thanksgiving. There is no camping at any of the three offroad locations, but a campground is 1 mile northwest of Huckleberry Roaks Area along N Hill Road.
Trail 2105 is in the Potomac River Area and is an alternative to 2201 to get to the Slag Pile from 2101. This is a straightforward trail until about halfway through, when you must climb a short rock field. It's nothing too difficult, but you'll have to concentrate if you don't want to damage your truck. There is potential for pinstriping.