Ship Island is part of the Mississippi barrier island chain, which consists of Cat Island to the west, and Horn Island and Petit Bois Island to the east. These islands lay between six and twelve miles off the Mississippi coast. Ship Island is located within the boundaries of the Gulf Islands National Seashore (GUIS) Mississippi unit under the National Park Service (NPS) jurisdiction. GUIS includes outstanding natural, cultural, and recreational resources along the northern Gulf of Mexico coasts of Mississippi and Florida.