Navigator: Boston Harbor Islands

The 34-isle archipelago, a protected national park, offers hiking, biking, and camping galore. 617-223-8666, bostonharborislands.com; ferries, 617-222-6999, harborexpress.com.

History buffs love Georges Island and its Fort Warren, an old prison for Confederate soldiers. The structure's dark passageways are refreshingly cool in hot weather, but it's the Lady in Black—the resident ghost—that's really shiver-inducing.

Boston Light, America's oldest lighthouse, welcomes camera-toting tourists to Little Brewster Island. Its first-ever female keeper, dressed in traditional Colonial garb, leads tours of the building. (Don't say we didn't warn you: There are 76 spiral steps to the top.)

The wooded trails on bucolic Grape Island are secluded enough to make campers forget they're in the shadow of New England's largest metropolis. Bonus: no bears!

Travelers prone to seasickness can skip the ferry and drive to Nut Island, a peninsula connected to the mainland via Quincy. Walk amid a blanket of wildflowers or cast a line for stripers and blues off the fishing pier.

Among the diverse attractions on Peddocks Island are heron rookeries, an abandoned military fort, and the isles' last remaining summer-cottage colony. Leonardo DiCaprio filmed scenes here for his upcoming thriller, Shutter Island.

Hop the May-through-October ferry to Spectacle Island for a morning on its sandy, lifeguard-staffed beach. Fuel up at the visitor center/café before hiking to Spectacle's 157-foot-high "peak" and taking in the Boston skyline.