Harbor Islands hiking.
I bought a groupon type deal many months ago for a discount on the boat rides to Georges and Spectacle Islands.
Really a great National Park. Spectacle is basically a capped garbage pile and Georges is a fort from the early 1800's. Really nice historical displays of how naval defense progressed over the decades.
Of course, none of these many forts along the east coast ever saw any action over the past 160 years. One wonders how much better a country could do economically if it didn't spend huge sums on the military.
View from the range spotting tower at Fort Warren