Divers searching for the last resting place of an American Civil War Confederate ship may be a step closer to solving the 150-year-old mystery.

Mark Diel, owner of Dive Bermuda, said divers looking for the Roanoke wreck as part of an American TV show had discovered an anchor and chain that appeared to match the missing ship.

Mr Diel said: “We found a beautiful anchor with significant amount of chain that looks like it came from that era and would be about the right size for that boat.

“Pictures of that are being sent off to people who have a lot more knowledge than we do about this to see if they can shed some light on it.

“Some wreckage in the right area was found but it’s heavily buried in the sand so it’s going to need some excavation. But it’s exciting and promising.”

Mr Diel was one of the divers who teamed up with underwater explorer Philippe Cousteau — grandson of undersea exploration giant Jacques Cousteau — and his wife, Ashlan, in April to try to find the wreck.

The couple were inspired by an article Mr Diel wrote on the mystery for an American-based diving magazine.

Their search was filmed for the Travel Channel series Caribbean Pirate Treasure and aired on Wednesday.

Mr Diel said the Cousteaus were “so pleasant and helpful to those of us who hadn’t done this sort of thing before”. He added: “It was a really pleasant experience — a lot of fun.”

Dive Bermuda worked with Chris Gauntlett’s Blue Water Divers and other local divers, including Philippe Rouja, the Custodian of Historic Wrecks, on the shoot.

Mr Diel said: “I thought it was very well done and, as Dr Rouja said, they handled the historical aspect of it really well.”

He added: “The footage that they got just about Bermuda in general and the aerial footage is a great plug for the island, no question.”

Mr Diel explained that about 20 divers took part in a one-day search in the Five Fathom Hole area to the east of Fort St Catherine in St George’s.

“We were ever hopeful of coming across the paddle wheels or the boilers or the smoke stacks or something really definitive — but we haven’t yet,” he said.

“The wine bottles in the Mary Celeste were there for 150 years and people were diving on that wreck for 40 years until after one particular storm, they were found.

“This stuff could be under eight inches of sand and we would never know it.”

Mr Diel said if the anchor belonged to the missing ship, the chain attached to it would give a good indication of where the wreck might be.

But he added: “It’s baby steps at this stage. It’s amazing how difficult it is to find something out there even when you know the general area you should be looking at.

“We know it’s there. That’s the funny part about it. We know it’s in Five Fathom Hole but it’s about a square mile of area so it’s just a question of being able to locate it.”

The divers also found other anchors but they did not appear to be the right period or size for the Roanoke.

The Union steamer was hijacked en route from Cuba to New York by Confederate sailors who had joined the ship in Cuba in disguise.

The Confederate seamen diverted to Bermuda for coal and to disembark the Union crew and passengers. But the Governor of the day refused to resupply the ship because he regarded its seizure as an act of piracy and Bermuda, as a British territory, was neutral during the US Civil War.

Confederate Lieutenant John Braine, who had taken command of the Roanoke, put the passengers and crew in lifeboats and scuttled the ship to avoid its recapture by Union forces.

Dr Rouja said the show gave people “a nice taste of how interesting and entertaining Bermuda history can be”.

He added: “Bermuda has played an integral part in maritime history and, as a consequence, there are literally shipwrecks and stories from every century since 1500. We have many more stories to tell.”