Biking -- Bikers and hikers can access the towpath of the Chesapeake & Ohio (C&O) Canal at Point of Rocks, off Route 15 South; Brunswick, Route 79 off Maryland Route 340; or Sandy Hook, left off Route 340, before you cross the Potomac River. The canal runs along the Potomac for 185 miles from Georgetown to Cumberland. Bicycle bells are required on the towpath. The Western Maryland Railway trail, a 23-mile paved path, is accessible off I-70 at Exit 12, Big Pool.
Nearby, both Antietam National Battlefield and Gettysburg National Military Park are terrific sites to tour on bike.
Rent a bike at Wheel Base, 229 N. Market St., Frederick (tel. 301/663-9288). They sell and service bikes, too.
Hiking -- The Appalachian Trail (www.appalachiantrail.org) runs along the border of Frederick and Washington counties, through Washington Monument State Park, South Mountain State Park, Greenbrier State Park, and Gathland State Park. You can hike the entire Maryland portion in 3 or 4 days, but any section of it makes a great 1-day excursion.
North of Frederick, off Route 15, Catoctin Mountain Park (tel. 301/663-9388) and Cunningham Falls State Park (tel. 301/271-7574) offer several miles of easy to strenuous hiking trails.
