Franconia Notch State Park, Franconia, N.H.
Crowded in the summer and fall, this 9-mile trail will be practically all yours in the winter. The trail starts at the Flume, an 800-foot-long gorge with steep walls. Next stop is the Basin, a granite pool 30 feet wide and 15 feet deep. Called a pothole by geologists, this strange cavity was formed by a melting ice sheet 15,000 years ago.