 The township borders Bordentown City, Chesterfield Township, Fieldsboro, Florence Township and Mansfield Township in Burlington County; Hamilton Township in Mercer County; and Falls Township across the Delaware River in Pennsylvania.Crosswicks Creek and its juncture with the Delaware River, otherwise known as the Trenton-Hamilton Marsh, is a significant ecosystem and, with the peninsula of land and waterways to the northwest of Bordentown Township known, respectively, as Duck Island, Duck Creek and the Delaware and Raritan Canal, it is protected by the State of New Jersey as the Duck Island Recreation Area.Unincorporated communities, localities and place names located partially or completely within the township include Bossert Estates, Dunns Mill and Newbold Island.