SAN JUAN, Puerto Rico - A U.S. underwater archeology team announced Thursday it has likely discovered the shattered remnants of a ship once captained by the notorious buccaneer William Kidd off a tiny Dominican Republic island.

The barnacled cannons and anchors found stacked beneath just three metres of crystalline coastal waters off Catalina Island are believed to be the wreckage of the Quedagh Merchant, a ship abandoned by the Scottish privateer in 1699, Indiana University researchers said.

"When I first looked down and saw it, I couldn't believe everybody missed it for 300 years,'' said Charles Beeker, a scuba-diving archeologist who teaches at Indiana University.

"I've been on thousands of wrecks and this is one of the first where it's been untouched by looters.''

Beeker said the wreckage has been aggressively sought by treasure hunters, including a group with a permit from the Dominican government to scour Catalina for remnants of the ship, which historians believe was scavenged of treasure and burned shortly after Kidd abandoned it.

The Dominican government has licensed the U.S. university to study the wreckage and convert the sea floor where the cannons and anchors are marooned into an underwater preserve, where it will be accessible to divers and snorkellers.

"We believe this is a living museum,'' said Beeker, who has previously helped the Dominican government open underwater parks that feature cannons, jar fragments and other items recovered from early 18th-century shipwrecks.

"The treasure in this case is the wreck itself.''

The scattered cannons and anchors, partially hidden by swirling sand, were first spotted by a local man who reported his discovery to the Dominican government, said Francis Soto, director of the National Office of Subaquatic History and Culture.

The Indiana University team then examined the wreck at the request of the Caribbean country's government.

The find will likely reveal key information about piracy in the Caribbean and about the elusive Capt. Kidd, said John Foster, California's state underwater archeologist, who will participate in the research.

"I look forward to a meticulous study of the ship, its age, its armament, its construction,'' Foster said.

"Because there is extensive written documentation, this is an opportunity we rarely have to test historic information against the archeological record.''

Historian Richard Zacks, who wrote a book about the seafaring privateer called "The Pirate Hunter: The True Story of Captain Kidd,'' said the Scotsman captured the 454-tonne Moorish ship in the Indian Ocean but left it in the Caribbean in 1699 as he travelled to New York to try and clear his name of criminal charges.

Kidd failed to persuade authorities of his innocence and was hanged in 1701 in London, Zacks said. His body was suspended in a gibbet, a kind of cage, on the Thames River as a warning to other privateers.