Several smaller islands, though geographically distinct, are in proximity to Long Island and are often grouped with it. These islands include Fire Island, the largest of the outer barrier islands that parallels the southern shore of Long Island for approximately ; Plum Island, which was home to the Plum Island Animal Disease Center, a biological weapons research facility; Fishers Island and smaller islands Wicopesset Island, North Dumpling Island, South Dumpling Island, and Flat Hammock; as well as Robins Island, Gardiners Island, Long Beach Barrier Island, Jones Beach Island, Great Gull Island, Little Gull Island, and Shelter Island.