Print Collector via Getty Images A late 19th-century engraving from "Picturesque Atlas of Australasia, Vol I" by Andrew Garran shows the HMS Endeavour aground on the Great Barrier Reef in 1770.

One of the most famous lost ships in history may have just been found.

James Cook's Endeavour -- a ship that vanished off the map so completely that there are accounts of its possible final location across the globe -- may be in the waters off Newport, Rhode Island.

The Rhode Island Marine Archaeology Project (RIMAP) will announce on Wednesday that it is between 80 percent and 100 percent certain it knows the location of the legendary explorer's lost ship, according to information on its website.

The organization said Endeavour was renamed the Lord Sandwich after Cook's first voyage, used as a transport ship for British soldiers in the American Revolution, and then scuttled in Newport Harbor during the August 1778 Battle of Rhode Island.

RIMAP used documents from London to discover that the HMS Endeavour/Lord Sandwich was one of 13 ships that sank in the harbor during the battle. The organization believes the ship is in a specific area where five ships were scuttled, and it has already mapped four of the wreck sites there.

Print Collector via Getty Images A wood engraving showing the HMS Endeavour off Australia.

Cook used the ship during his 1769-1771 journey around the world.

While he was not the first European to encounter either New Zealand or Australia, he was the first to circumnavigate New Zealand and the first to land on the east coast of Australia, which he named New South Wales, during the voyage.

He claimed both for Britain.

Cook also "discovered" the Great Barrier Reef by running aground on it in 1770. His crew was able to free the ship and bring it to what he named the Endeavour River for seven weeks of repairs.

Cook's explorations of the region have made him a national hero in Australia, and the Australian National Maritime Museum provided a grant to fund part of RIMAP's work.

RIMAP said:

"All of the 13 ships lost in Newport during the Revolution are important to American history, but it will be a national celebration in Australia when RIMAP identifies the Lord Sandwich ex Endeavour. So for RIMAP to be closing in one of the most important shipwrecks in world history, for that ship to be found in Newport, and for it to have an international reputation, should be an intriguing birthday gift for all of Rhode Island."

Rhode Island celebrates its 240th birthday on Wednesday, having disavowed the King of England on May 4, 1776.

De Agostini / G. Nimatallah via Getty Images A scale model of the HMS Endeavour.

While RIMAP first uncovered documents in the 1990s suggesting that Endeavour was scuttled off Rhode Island, there have been multiple competing accounts of its final destination.

One version of events has the ship wrecked off New Zealand, another suggests it spent its final days working on the Thames in Britain, and a third version says the ship was used by the French as a whaling vessel before eventually running aground and being broken up, according to the Captain Cook Society, a group dedicated to the explorer.

"There is a great deal of controversy and very little that can be regarded as authentic" when it comes to the location of the ship, N A Maffey wrote in the 1970 book Captain Cook's Ship, H.M. Bark Endeavour, according to the Society.

If RIMAP is correct, the mystery may have just been solved.

The organization plans to determine which of the five harbor shipwrecks is that of the Lord Sandwich/Endeavour with "more intense study of each vessel's structure and its related artifacts."