This Yorkville swimming hole is right at the edge of the East River, and visitors can spy Roosevelt Island from a pedestrian bridge linking John Jay Park with the East River Esplanade across the FDR. The 145-foot-long pool itself is lined with leafy trees, setting a bucolic scene for a dip or poolside lounge. At the diving area, kids can practice cannonballs, pikes, twists and jackknives with impunity. Even when the pool is at capacity on weekend mornings, it still feels spacious. Show up with your brood around 5pm on a weekday and you'll have the place mostly to yourselves. Unfortunately, though, there's no baby pool and little shade, which means you'll find an older and rowdier crowd.