The Lasker Pool is a little-known area in Central Park right next to Harlem Meer at the very north tip of the park. What's great about it is that you can swim here for free all summer long. The only thing you need to know is that they don't allow newspapers (it would scatter I guess) and you have to lock up your valuables in lockers, so bring a lock. But if you come with a towel, shower shoes and swimming gear, this place is perfect for a hot summer's day. Convenient to both the Upper West and Upper East sides.