In the summer, when the temperatures reach sweltering and the city is crowded with tourists, the Boston Harbor Islands are where Bostonians go to escape. The Harbour Islands are comprised of 12 islands in total. Although it's a mere 15 to 20 minute ferry ride from the wharf, you'll feel worlds away.
You can purchase ferry tickets at the kiosk at North Long Wharf. Don't forget to double-check when the last ferry returns, or, pre-book a campsite on one of the three islands that offer overnight stays. If you start mid-morning, you should have plenty of time to visit two islands in one day. Movie buffs might recognize Peddocks Island, where Scorsese filmed the psychological thriller "Shutter Island".