The treasure of the oceans: rise of the salvagers

Captain John Limbrey was a not poor man. When his ship the Merchant Royal put into Cadiz harbour for repairs in January 1637, his personal fortune was estimated at 100,000 gemstones. But in the buccaneering and avaricious spirit of the times, he could not pass up the opportunity to make a little more.

For this powerful veteran of the treacherous trans-Atlantic trade routes, opportunity came knocking when fire broke out on board a ship employed to transport silver coins, ingots and gold to 30,000 Spanish troops stationed in Flanders. Limbrey was only too happy to offer his and his crew's services and in August 1641 his 700-ton vessel set sail for the Netherlands in convoy with its sister ship the Dover Merchant. What followed was one of the great calamities of the mercantile era.

The Merchant Royal sprung a leak 35 miles off Land's End and sank in heavy seas with the loss of 18-crew and its entire treasure chest. It is estimated this was equal to one-third the value of the national exchequer. The Long Parliament, then on a revolutionary collision course with Charles I, was interrupted with the news while pamphlets carried breathless accounts of the disaster.

Limbrey was devastated by the loss, not only of his men but also of his treasure, though he recovered sufficiently to play a pioneering role in the ruthless colonisation of Jamaica, a key staging post in the slave trade for the next two centuries.

But if 17th-century mercantilism was a mucky business, an unexpected legacy bequeathed by ill-starred ships such as the Merchant Royal is proving equally contentious and conjuring the kind of drama and romance that only sunken galleons, treasure seekers and lost booty can.

There is mounting concern among marine archaeologists, academics and heritage groups at the activities of commercially driven salvage teams currently scouring the ocean floor checking out the worth of the estimated three million wrecks that languish there. Not all of them are laden with glittering baubles, but there are enough – around 3,000, according to some estimates – to drive the kind of high risk, get-rich-quick adventure business that would have set Captain Limbrey's pulse racing.

But the search for submarine treasure is running into choppy seas. This month the master of the Odyssey Explorer, a diving support vessel owned by the Nasdaq-listed company Odyssey Marine Exploration, was arrested and put in jail in Algeciras in Spain.

In May, Odyssey stunned the world when it announced that it had recovered 500,000 silver coins weighing 17 tons from a vessel it would describe only as the fictional "Black Swan" after the 1942 swashbuckling Hollywood classic of the same name. The coins, said to be worth £250m, were taken to Gibraltar and then on to Florida where the question of ownership is now being settled in the courts.

The British media were certain that the booty came from the Merchant Royal. The Spanish press remain equally convinced that it was instead recovered from the Nuestra Senora de las Mercedes, a Spanish warship sunk by the British off Portugal.

Odyssey refuses to reveal exactly where it found the treasure, insisting it cannot identify with certainty the vessel on which it was found. The scrutiny of the bounty continues.

But campaigners say the different reactions by British and Spanish governments reveal that when it comes to their respective underwater cultural heritage, the two nations are oceans apart. Spain has already lodged a counter claim with the Floridian court seeking ownership of the coins, and has taken steps to stop and search the Explorer. In Madrid, ministers have been engaged in some serious sabre rattling describing the treasure seekers as "modern pirates."

"Nobody can come and sack our patrimony, as if on top of that they were doing us a favour. We will follow and persecute them no matter where," thundered culture minister Cesar Antonio Molina.

The British government, by contrast, has agreed to a lucrative deal splitting the proceeds with Odyssey if it recovers the war chest of another sunken ship, the HMS Sussex, which went down off Gibraltar in 1693 with £250m in today's money on board.

Dr David Gaimster, general secretary of the Society of Antiquaries, believes time is running out for the world's most important wrecks with the ever-growing fleets of private treasure hunters taking to the seas bristling with the latest in sonar, GPS and remotely operated vehicles.

"For generations these hugely important sites were safe because they were too far down to be safely reached. But improvements in technology mean they are now quite easily accessible. These irreplaceable cultural resources are now being stripped. They are not being archaeologically recorded but looted for profit with the bullion and other precious metals being melted down or sold to collectors ...with the result that they are lost for ever," he said.

Odyssey, which recently signed a joint venture scheme with the Disney organisation, says it operates to the highest legal and ethical standards.

The work to recover the coins at the Black Swan site has "diligently followed archaeological protocols using advanced robotic technology and the artefacts [were] ...now undergoing a meticulous conservation process by some of the world's most experienced coin conservators," it says.

But making money of modern day treasure-seeking is proving problematic, and recovering booty is not cheap, as the "serious" archaeologists know. This month the Mary Rose Trust said it needed a further £35m to complete the restoration of Henry VIII's warship raised from the Solent 25 years ago.

In its most recent financial statement, Odyssey reported a second-quarter loss of more than £3m and falling revenue compared to 2006 though it still seems to be attracting capital to back it. Last week it emerged that Fortress Investment, a listed hedge fund, had injected £3.5m into the enterprise.

Back in the UK pressure is mounting on the British Government to follow Spain by signing up to the 2001 Unesco Convention on the Protection of the Underwater Cultural Heritage. Continued resistance from the British and United States governments, gave the green light to profiteers seeking to scoop up the fabulous wealth languishing beneath the waves, it is claimed.

Britain opposes blanket protection for wrecks believing it should concentrate on saving only the best. However, in 2005, on the bicentennial anniversary of the Battle of Trafalgar, heritage groups issued the Burlington House Declaration, calling on the Government to sign up to the convention. It currently has 16 signatories – four short of the 20 it needs to protect the vast majority of the world's wrecks.

More recent treasures are also at stake with sites such as Jutland, where more than 8,000 British and German seamen died in the only full-scale sea battle of the First World War, or the Titanic, also under threat.

For Robert Yorke, chairman of the Joint Nautical Archaeology Policy Committee, organisations such as Odyssey operate with little more than a "veneer of archaeology". "It is very difficult to recover seven tons of coin without destroying the organic material such as the barber surgeon's chest or the musical instruments that we found in the Mary Rose and tell us so much about life at that time. That sort of archaeology is incompatible with a ship that costs hundreds of thousands of dollars a day to run and when you are working with shareholders on the Nasdaq," he said.

Meanwhile, out in the Western Approaches off Cornwall, work to locate the Merchant Royal continues. "They say they have a very large number of targets – over 100. The situation is that now they can see these things and nothing is safe and we have no control. It is very upsetting," said Mr Yorke.