Outer Banks or the Banks, chain of sand barrier islands and peninsulas, c.175 mi (280 km), along the Atlantic coast of SE Va. and E N.C. Separated by inlets and enclosing several saltwater lagoons, or sounds, the main islands, from north to south, are Bodie, Roanoke, Hatteras, Ocracoke, Portsmouth, and Core Banks; the islands and peninsulas south of Core Banks to Smith Island are sometimes not considered part of the Outer Banks. Three prominent capes, Cape Hatteras (Hatteras Island), Cape Lookout (Core Banks Island), and Cape Fear (Smith Island), mark the locations of shifting Atlantic shoals that are the graveyards of many ships. The Banks are generally 1 mi (1.6 km) wide or less, and are subject to frequent hurricanes. Cape Lookout and Cape Hatteras national seashores and Pea Island National Wildlife Refuge are in the Banks, which are a popular vacation area. Behind the Banks, Currituck Sound begins S of Back Bay in SE Virginia, expands into Albemarle Sound, narrows into Croatan and Roanoke sounds (between which lies Roanoke Island), expands again into Pamlico Sound (the largest by far), then narrows again in Core and Bogue sounds. South of Bogue, the Banks are separated from the mainland largely by the still narrower channel of the Intracoastal Waterway, part natural, part canal. Several large estuaries extend inland from Albemarle and Pamlico sounds.