Haddam Island State Park occupies a fourteen-acre island in the lower Connecticut River at Haddam, Connecticut, accessible only by boat and valued more as a natural river preserve than a developed park. First known to English settlers as Thirty Mile Island, it was part of land sold by the Wangunk tribe in 1662, with some use rights reserved and later sales continuing into the eighteenth century. By the late eighteenth century it had become an important fishing place, and in the nineteenth century it supported fishing operations, grazing, and corn. Connecticut purchased the island in 1944, and it is now prized for birdlife, migration research, and simple outdoor recreation.