Prudence Island
The reserve encompasses 2,353 acres (9.5 km²) of land as well as 1,591 acres (6.4 km²) of water adjoining the islands out to a depth of . During the colonial era, all three islands were used for farming. By the 20th century, farming had declined and Prudence Island began to attract summer residents. During World War II, the U.S. military established a presence on the island and remained until 1972, when the land was turned over to the state of Rhode Island.