Duxbury Bay is a bay on the coast of Massachusetts in the United States.[1] The west shore of the bay is the town of Duxbury, Massachusetts; and the bay is formed by a sandbar called The Gurnet extending southeasterly from Marshfield, Massachusetts into Cape Cod Bay. The town of Marshfield was named for the estuarine wetland at the north end of the bay. The bay opens southerly toward Plymouth, Massachusetts between Captains Hill to the west and Saquish Head to the east.