Atlantic Beach is an affluent village off the South Shore of Long Island in the Town of Hempstead, Nassau County, New York, United States. It is located on Long Beach Barrier Island, one of the outer barrier islands which it shares with Long Beach, East Atlantic Beach, Atlantic Beach Estates, Lido Beach and Point Lookout.As of the 2010 United States Census, the village population was 1,891.During the summer months, the population swells by thousands as people flood the beaches. Atlantic Beach residents may obtain season passes and access the beaches through nine entrances.In the 1980s Nancy McCartney the third wife of Beatle Paul McCartney lived there with her ex husband Bruce Blakeman.