Deep sea treasure: 17th century gold chain worth $250,000 plucked from ocean bed

A deep sea diver has struck gold after unearthing a 17th century chain worth $250,000 from the ocean floor.

Bill Burt, a diver for Mel Fisher's Treasures, spotted the 40-inch gold chain while looking for the wrecked Nuestra Senora de Atocha, which sank off the Florida Keys in a 1622 hurricane.

Shipwreck experts have tentatively valued the piece at around $250,000.

The chain has 55 links, an enamelled gold cross and a two-sided engraved religious medallion featuring the Virgin Mary and a chalice.

On the edges of the cross there is engraved wording thought to be in Latin.

Andy Matroci, captain of Mel Fisher's Treasures salvage vessel, JB Magruder, said the crew had been diving at the North end of the Atocha trail.

On their last trip to the wreck they uncovered 22 silver coins and a cannon ball just east of the site.

They had been hoping to find more coins in the area, Mr Matroci said, but instead found the chain.

'In the nine years I have been running this boat this is the most unique artefact we have brought up,' Mr Matroci said.

The piece is believed to be from the Atocha's infamous treasure trove.

The company has uncovered half a billion dollars in historic artefacts, gold, silver and emeralds since they began diving the wreck in 1969.

In 1985 - after 15 years of searching - the Fisher crew discovered Atocha's 'mother lode', worth more than $450million.

They unearthed thousands of artefacts, silver coins, gold coins - many in near mint condition, exquisite jewellery sets with precious stones, gold chains, disks, a variety of armaments and even seeds, which later sprouted.

They then faced a legal wrangle with the U.S. Government claimed title to the wreck. Florida state officials seized many of the items the Fisher crew had retrieved.

But after eight years of litigation, the U.S. Supreme Court ruled in Fisher's favour.

The contents of the ships sterncastle - a wooden, fort-shaped area at the back of ship, have never been recovered.

This is where the wealthy passengers, including nobility and clergy, would have stayed.

Fisher's estimates the treasure in the sterncastle section is worth in the region of half a billion dollars.

The latest find was likely owned by a member of the clergy indicating the company's search for the missing treasure trove could be getting nearer.