Custer State Park
13329 US Highway 16A
Offers a number of nice hiking trails, including several routes to harney peak, highest point in the state of south dakota. several of the trails that start in the state park continue on into the national forest's black elk wilderness.
Mickleson Trail
The Black Hills bicycle trail, the Mickleson Trail, is remarkable. It is gravel and runs along an old railroad track. It will have a very gentle uphill grade for several miles, and then a gentle downhill grade for several more miles. It stretches for 100 miles up through the hills hitting several cities such as Custer and Hill City, and passes right by the Crazy Horse monument.