Manhasset Bay, New York, is an embayment in western Long Island off Long Island Sound. Manhasset Bay forms the northeastern boundary of the Great Neck Peninsula and the southwestern boundary of Cow Neck (Port Washington Peninsula or Manhasset Neck). On the north side of the bay there are three points, Barkers Point at the entrance, Plum Point coming the furthest into the Bay, and Tom's Point in the back bay. On the other side, Hewlett Point forms the entrance nearly a mile from Barkers Point. Hart Island lies in the Sound just outside the mouth of Manhasset Bay.