Deer Island is one of the Fundy Islands in the Bay of Fundy, Canada. It is at the entrance to Passamaquoddy Bay. The island was first settled by colonists around 1770. Local government is provided by the West Isles Local Service District, which is within the Southwest NB Regional Service Commission. At 45 km2, it is the largest island in the West Isles Parish CSD, which had a 2021 population of 718. It has three communities: Fairhaven, Leonardville, and Lords Cove. There is a primary school on the island, while older pupils attend Fundy High School on the mainland.