Concord Coach’s Maine Coastal Route runs bus service between Boston and Bangor Maine.
Bus schedule for Maine coastal Route One service to and from Boston South Station, Logan International Airport and points in between. This route includes: Brunswick, Bowdoin College, Bath, Wiscasset, Damariscotta, Waldoboro, Rockland, Camden/Rockport, Lincolnville, Belfast, Searsport, and Bangor, ME.
With these stops the travel time is increased significantly over a direct travel, however, it is the more Green way to go.
Link to the Coastal Route 1 Bus Schedule