Almost anywhere you stand along a Portland shoreline you will see some of the Casco Bay Islands. There are over 200 of them. Seen here from the Eastern Promenade are Mackworth Island (center) and Great Diamond Island (right). Six of the major islands are served by ferry. For a real scenic treat, consider the Mailboat Run aboard the Maquoit II. While this working vessel is delivering packages and cargo, you will enjoy the archipelago of Casco Bay for 2.5 to three hours. The tour is provided by Casco Bay Lines located at the Maine State Pier near the cruise terminal.