Which Way to the (Hidden) Beach?

On the southern shore of Queens, away from scolding lifeguards and crowded boardwalks, a former military base has become one of New York's great hidden beaches. There at Fort Tilden, some beachgoers go topless and some forage the dunes for driftwood with which to build makeshift shelters with sheets and blankets. Mariana Garay, her husband and their two sons (one of whom is in the center picture on the next page) have driven down to Fort Tilden from Williamsburg, Brooklyn, on summer weekends for the past three years. ''You're not surrounded by people selling things and eating hot dogs or lifeguards who are always blowing their whistles,'' Garay says. ''It's a different vibe, more lonely and quiet.'' But it isn't flawless. ''It's not the cleanest ocean,'' she adds. ''It's still New York, you know.'' Beach at Coney Island: 107 acres [ABSTRACT FROM AUTHOR]