It dates from the mid-19th century, a 22-acre park connected to the mainland by both pedestrian and vehicular causeways. There’s also a “healthy heart” trail.

The 155-acre lake here has been part of Cambridge’s reservoir system since the 1850s, and has 162 wooded acres surrounding it. These acres include a 2.25-mile perimeter road for jogging, biking, walking, sprinting, you get the picture. Serious bird-spotting available, too. Flowers, ditto. Serious.

The roots of Nathan Tufts Park near Powder House Square and Tufts’ campus go back four centuries. Its old Powder House stone tower was originally built as a windmill by European settlers.

Take the Blue Line to Maverick Square and walk a bit (or, someday, hop a ferry), and experience Piers Park’s 600-foot pedestrian promenade, which leads to two pavilions with killer skyline views. There’s also an amphitheater, an outdoor fitness system and a large playground.

Wanna fish or watch people fish? This relatively new, 5-acre park (completed in 2007) includes a pier overlooking Boston Harbor with fish-cleaning stations that, according to the city, make it a “perfect spot for some friendly fishing.” It’s about a 10-minute walk from North Station.

After you’ve done the 2.6-mile perimeter, with its sweeping Harbor views, why not visit the Deer Island Wastewater Treatment Plant and learn about how that same Harbor got so clean? Why, indeed. Also a good vantage for watching planes taking off and landing at Logan. Is that the Dreamliner we see taking to the skies again?

So there you are on the Red Line thinking, "Good god, where's there a good beach in walking distance from one of my next stops?" It's here! Minutes from the JFK/UMass stop! It got new sand last year as well as new walkways, benches, lighting and shade shelters.

Take the Blue Line to the Orient Heights stop (or the bus, which stops at the Bennington Street entrance), and enjoy an open beach with lifeguards, a bathhouse (with concessions) and a big playground (and tennis courts).

Here be your best chance of spotting a porpoise within Boston city limits! This former marine industrial site was redeveloped into an urban wild with salt marshes, meadow grasses, walking paths, a boardwalk, sculptures, and a viewing platform overlooking Chelsea Creek. Take the Blue Line to Maverick.