Turtle Mound is a prehistoric archaeological site located 9 miles (14 km) south of New Smyrna Beach, Florida, on State Road A1A. On September 29, 1970, it was added to the U.S. National Register of Historic Places. It is the largest shell midden on the mainland United States, with an approximate height of 50 feet (15 m). The mound extends for over 600 feet (180 m) along the Indian River shoreline and contains over 35,000 cubic yards (27,000 m3) of shells. Turtle Mound was estimated to be 75 feet (23 m) high before it was reduced by shellrock mining in the 19th and 20th centuries. Because it is visible seven miles out at sea, early Spanish explorers and subsequent mariners used the large mound as a landmark for coastal navigation. Today, the site is owned and managed by the National Park Se