Sounds ominous, but the mail boat runs from the Portland ferry terminal and drops off and picks up cargo & passengers from the various islands outside the city in Casco Bay. There is a narrated tour, lots of seats inside & out but the facilities are spartan and even in August it can be chilly so come prepared. At every stop as the boat pulls away the local kids all dive off the dock into the froth created by the boat – what a slice of Americana. We brought some wine and a picnic and rode in style!!