- Come aboard the Isle Au Haut mailboats and escape to beautiful Acadia National Park or sit back and relax on a wonderful sightseeing excursion around some of the many islands in Penobscot Bay. We offer passenger and freight service between Stonington and Isle au Haut, excursions for sightseers and seasonal service to Acadia National Park at Duck Harbor. Click above on the ISLAND INFORMATION ...www.isleauhaut.com