Enlarge Image North Carolina Office of State Archaeology/Institute of International Maritime Research

There's a historical enigma lying on the bottom of the Atlantic Ocean off the coast of North Carolina. A sonar search of the ocean floor in late February revealed an iron-hulled steamer ship dating to the days of the Civil War, a conflict that lasted from 1861 to 1865.

Famous Civil War land battles like Gettysburg and the First Battle of Bull Run may dominate general knowledge, but the warfare spilled into the Atlantic in the form of Union blockades designed to cut off trading to the Confederates in the South. There were also conflicts between armor-plated ironclad warships.

The wreck appears to be a blockade runner, a steam-powered ship built to evade the Union blockade. The North Carolina Office of State Archaeology announced on Monday the discovery from near the mouth of the Cape Fear River. The office notes this "is the first Civil War-era vessel discovered in the area in decades."

"The state of preservation on this wreck is among the best we've ever had," Billy Ray Morris, an archaeologist with the North Carolina Office of State Archaeology, said in a statement. He describes the wreck as "a really big deal."

There are three likely candidates for the vessel's identity. The Agnes E. Fry, Spunkie and Georgianna McCaw are all blockade runners known to have gone down in the area where the wreck was found.

Last year, a research vessel examined an even older shipwreck off the coast of North Carolina. Submersibles went in for a close look at the ship, estimated to date as far back as the late 1700s, and discovered glass bottles, a metal compass, a navigational instrument and an iron chain.

Scientists will continue to investigate and gather data on the shipwreck site as weather allows. There is no word yet on whether or not they plan to dive down or send submersibles to the ship.