As New England's only national park, Maine's Acadia National Park is relatively small but still draws nearly three million visitors each year. Most of the park centers around Mount Desert Island which has a 20-mile Park Loop Road with fantastic views and a path to Cadillac Mountain. Fit hikers should attempt the Precipice Trail, which is the most challenging and well-known attraction in Acadia National, with an almost vertical 1,000-foot climb. 

Don't Miss: The Schoodic Peninsula, the only portion of the park on the mainland, has similar scenery to Mount Desert Island but is far more secluded. In the 1930s and 1940s, some of this area was transferred to the Navy to be used as a radio communication station, but was given back to the Park Service in 2002. For easy sightseeing, take the six-mile, one-way loop of road around Schoodic to see the sea birds that call the peninsula home.