Along the waterfront near the downtown Old Port district, the family-owned Harbor Fish Market is a 40-year-old shop prized by locals for its reliable excellence. Pristine scallops glisten in cases, and the air smells of ocean brine. Order a lobster to go (the staff will cook it for you), and then stroll up Commercial Street to picnic-perfect Eastern Promenade Park, a grassy bayside expanse. —Meeghan Truelove
9 Custom House Wharf, (207) 775-0251, harborfish.com.