We'll have a day in Portland in early October as the 1st stop of a cruise. We've been to Portland before, love the area, but would like to keep this low key and relaxing. Last trip we noticed all the inter-island ferries leaving from very close to the cruise ship pier. Would hopping on one of them make an interesting day trip? If so, which island/islands would you recommend, including a stop for a nice lunch? We have somewhat limited mobility so don't want strenuous hiking; we're mostly interested in just getting off the beaten track, absorbing gorgeous scenery, getting a few great photos, maybe a lobster roll and a slice of blueberry pie!