This 1.5 mile stretch of parks along the East River is a good way to try to escape the hustle and bustle of the city, while still being only a train ride from Manhattan.
Starting at the Brooklyn Main Street Park, you are on the right side of the Manhattan Bridge. Here you can check out the new outdoor climbing gym. Keep walking along the water and you'll soon come upon Pebble Beach. Now this beach is not exactly a "let's bring our beach chairs and spend the day here" beach; it's more of a "woah! there's a beach here?" beach. But do whatever makes you happy. Past that is a historical carousel that is being restored to it's prior glory. From here, you pass under the Brooklyn Bridge and you are officially in Brooklyn Bridge Park.
Take a walk down the rest of the parks along the river. There are six piers with boundless activities. Take a look at the map that shows all the amenities and attractions: including a roller skating rink!If you have kids and you want to make a day of this trip, check out the Environmental Education Center. Keep in mind it closes at 5PM.If your dog is your kid, bring them too! There's a Dog Run located in the Main Street Park.
There are also tons of places to eat around here. I didn't check any of them out, but why not if you're hungry? Or if you want to bring your own food, just post up on the grassy lawn and have a picnic.