Sheepshead Bay is a bay separating the mainland of Brooklyn, New York City, from the eastern portion of Coney Island, the latter originally a barrier island but now effectively an extension of the mainland with peninsulas both east (the neighborhood of Manhattan Beach) and west (the neighborhoods of Coney Island and Sea Gate). The mouth of the bay is about 1.0 mile (1.6 km) southwest of Marine Park, Brooklyn. The area is part of Brooklyn Community Board 15.