www.nps.gov/caha/index.htm.GRAVEYARD OF THE ATLANTIC MUSEUM: About 600 shipwrecks litter the Hatteras coastline, giving rise to its nickname, Graveyard of the Atlantic. Most of the wrecks have been blamed on Diamond Shoals, an area of shifting sand bars that extends 14 miles into the Atlantic. The Graveyard of the Atlantic Museum in Hatteras is dedicated to local seafaring history. The museum's focal point is a 12-foot-tall lens made in 1854 for the Cape Hatteras Lighthouse. It's known as the first-order Fresnel lens (first order refers to size, Fresnel was the name of its designer). Other artifacts include an Enigma machine from a German U-boat, used to encrypt and decode messages, and a display about Billy Mitchell, who proved in the 1920s that airplanes could sink battleships, an idea that other military leaders of the time openly ridiculed. In September 1923, Mitchell's bombers sank two obsolete warships off Cape Hatteras from the air to prove his point. The local airfield is named after him.Admission is free; donations are encouraged. Details at www.graveyardoftheatlantic.com/index.htm.BIRD WALKS, MOVING ISLANDS AND MORE: The U.S. Fish and Wildlife Service offers numerous opportunities to learn about nature, many of which are free. One new program teaches visitors (and maybe some residents) about barrier island migration and why the ocean keeps cutting into N.C. Highway 12, creating new inlets.About 400 species of birds live in the Pea Island National Wildlife Refuge, and the USFWS offers free tours three days a week from late spring to mid-autumn and at least once a week the rest of the year. Details at www.fws.gov/alligatorriver/spec.html.LIGHTHOUSES: The National Park Service charges admission to climb both the Cape Hatteras and Bodie (pronounced BAH-dee) Island lighthouses. But nothing stops visitors from looking at the lighthouses and admiring them from the ground.Bodie Island just underwent a $5 million makeover and was opened to the public in April for the first time in its 141-year history. The Cape Hatteras Lighthouse, recognized by its famous black-and-white barber pole stripes, is the tallest brick lighthouse in the United States. It was moved in 1999 to protect it from beach erosion.Details at www.nps.gov/caha/planyourvisit/climbing-the-cape-hatteras-lighthouse.htm and www.nps.gov/caha/historyculture/bodie-island-light-station.htm.FERRY FROM HATTERAS TO OCRACOKE: At the end of Hatteras Island, near the museum, you can take a free ferry from Hatteras Island to Ocracoke Island, which is still part of the national seashore. The ferry takes about 40 minutes.On Ocracoke, you can visit a British cemetery and the Ocracoke Lighthouse, built in 1823 and noted for its white exterior. The Ocracoke cemetery has four of the 34 victims from the HMS Bedfordshire, which a German torpedo struck and sank on May 12, 1942. A fifth body washed up on Hatteras Island and is buried there, next to a British sailor from the merchant vessel San Delfino, which was also torpedoed by the Germans. Details at www.nps.gov/caha/historyculture/british-cemetery.htm and www.nps.gov/caha/historyculture/ocracoke-island-lighthouse.htm.