Acadia National Park by emilienoelle
The first U.S. National Park created east of the Mississippi, Acadia is made up almost entirely of once-private land donated by ultra-rich tycoons, like John D. Rockefeller, who were concerned about the region's lasting preservation. It's a truly gorgeous, wild place with mountains, forests and cliffs stretching right down to the sea. There are miles and miles of hiking and bike trails as well a 27-mile loop road for sight-seeing from cars. You can swim at Sand Beach, climb Cadillac Mountain, roam the forests and see all kinds of wild animals including deer, moose and bald eagles, and although thousands of people visit each year it's very easy to find a spot where you can be alone with your thoughts.
It cost $20 for a one-week group pass (a group is however many people fit in your car) and $40 for a yearly pass, which is worth it if you plan on making more than one visit or staying longer than two weeks. Passes are available at the Park Visitors Centers in downtown Bar Harbor as well as the main Visitors Center at the Park's entrance on Eden Street.
Acadia is open all year, though many of the Park's roads are not. If you plan on doing some winter camping or cross country skiing you may want to check and see what's happening before you go.