Underwater explorers believe they have discovered treasure belonging to the notorious 17th-Century Scottish pirate William Kidd in the waters off Madagascar.

A 50 kg block of silver with inscriptions, which is now under armed guard on Sainte Marie island off the east coast of Madagascar. The bar was presented to Madagascar's president at a special ceremony in 2015.

The bar is imprinted with a ‘T’ and ‘S’ on one side and letters and numbers on the other, the meaning of which is currently unknown.

The joint U.S./U.K. archaeological research team believe there are many more such bars still in the wreck.

Captain William Kidd (1645 –1701) was a Scottish sailor who was tried and executed for piracy after returning from a voyage to the Indian Ocean.

One of the most infamous pirates of all time, Captain William Kidd was said to have amassed treasure worth £100,000 – £12 million now – before he was arrested for piracy and murder.
Scotsman Capt Kidd buried a cache somewhere on his travels and at his trial in London, in 1701, tried to barter his knowledge of its location in return for his life.

The Guardian reports that the silver bar was found in shallow waters off Sainte Marie island by a joint UK-US archaeological mission led by Barry Clifford, an underwater investigator who discovered the remains of William Kidd’s ship Adventure Galley in 2000.

He is typically perceived as either one of the most notorious pirates in history, or as one of its most unjustly vilified and prosecuted privateers. The latter view comes from the fact that his actions were allegedly less destructive and less lucrative than other pirates, yet he met a rather brutal end – he was hanged twice (the first attempt failed), before being covered in tar and hung from a gibbet over the river Thames.

“The son of a Presbyterian minister, Kidd was a buccaneer and a captain for a private British ship in the Caribbean for some years, but it is claimed he decided that he found piracy more rewarding after he was commissioned to sail to Madagascar on the Adventure Galley,” reports The Guardian.

“His most famous capture was a 400-tonne ship, the Quedah Merchant, which carried silver as well as silk, gold, sugar, opium and cloth.”

Kidd was captured in Boston in 1699 and sent to Newgate prison. The treasure found on his ship was valued at £30,000 (around £10 million today), but the remainder of his treasure was never found. The belief that Kidd had left buried treasure contributed considerably to the growth of his legend and has also given impetus to constant treasure hunts in places Kidd is known to have visited.

The treasure has never been found – but experts believe the bar of silver, itself worth more than £17,000 at today’s prices, could be part of the famous loot.

The fate of Capt Kidd’s treasure has prompted numerous hunts around the world over the last three centuries, and his exploits inspired author Robert Louis Stevenson when writing Treasure Island.

Mr Clifford presented the suspected treasure to Madagascar’s president, Hery Rajaonarimampianina and UK and US diplomats at a ceremony on the island.
Mr Vogl added that officials including UK ambassador to Madagascar, Timothy Smart, are hoping the discovery will ‘raise the profile of Madagascar, especially for tourists’.

Capt Kidd was tried not only for piracy but also on the accusation he murdered one of his crewmen in 1697.

His execution was not straightforward, with the noose around his neck twice breaking – but the third rope held firm.

It is believed that Kidd buried much of his treasure, with the legend going down in history in Robert Louis Stevenson’s

The wreck of Kidd’s Armenian ship Quedagh Merchant was found by archaeologists from the University of Indiana in 2007, after decades of competition between treasure hunters to uncover the 500-tonne vessel.

The ship was loaded with treasured satins, muslins, silver and gold that probably belonged to the British East India Company before being commandeered by Kidd in 1699.