A nonprofit marine archaeology and exploration team announced in July that it had found the shipwreck in Ocracoke Inlet, along the state's barrier islands.
Officials with Surface Interval Diving Company have said the wreckage could also be that of a Civil War-era vessel burned by retreating Confederate officers in 1861.
The wreck is about 40 feet longer than those Blackbeard commandeered in the early 1700s, which were 80 to 90 feet long, said the company's vice president, David Pope.
And one historian and Blackbeard expert, also citing the vessel's length, says it is unlikely that it is Blackbeard's ship.
"In my mind, the possibility that it's Blackbeard's last prize is probably one in 300," said David Moore, nautical archaeologist and historian for the N.C. Maritime Museum.
But the location of the wreckage makes the Blackbeard theory plausible.
Historical documents show that Blackbeard captured two ships in August 1718 off Bermuda — one carrying sugar and the other nearly empty.
Blackbeard allowed the ships' crews to take the empty vessel, but he kept the full one, Moore said.
He brought the vessel back to Ocracoke Island where he stripped it of its valuables, Moore said. Then he received permission from North Carolina Gov. Charles Eden to burn the ship under the pretense that it was leaky, he said.
Virginia Gov. Alexander Spottswood sent British troops after Blackbeard a short time later and the pirate died in a battle off the island on Nov. 22, 1718.
The diving company's president, Rob Smith, said he believed the vessel could be a lightship that was burned along with Fort Ocracoke as Union forces approached. The ships were used in the 19th century to light the way in and out of inlets.
The diving company has sent wood samples from the wreck for analysis and is continuing to investigate the site.