Marine archaeologists say they are "closing in on one of the most important shipwrecks in world history" — pinpointing its whereabouts to a cluster of five ships.
"All of the 13 ships lost in Newport during the Revolution are important to American history," the group said in a statement, "but it will be a national celebration in Australia when RIMAP identifies the Lord Sandwich ex Endeavour."
Researchers with the Rhode Island Marine Archaeology Project, a nonprofit organization that studies maritime history and marine archaeology sites, used historic documents in London to map out and analyze sites where the ship might be found on the sea floor.
Recent data analysis shows that there is an 80 to 100 percent chance that the ship is still in the harbor.
"Because the Lord Sandwich was Capt. Cook's Endeavour," the group said, "that means RIMAP has found her, too."
Cook learned the world's waters while serving in the Royal Navy, according to the BBC. In the mid-1700s, he was named the commander of the HMS Endeavour and sent on a scientific voyage in the Pacific Ocean.
From 1768 to 1780, he went on three voyages around the world, during which time he encountered Australia's southeastern coast and claimed it for Britain, according to the BBC.
A handwritten letter believed to have been written by Cook after his first trip to Australia was discovered in 2002, BBC News reported at the time. It let the Admiralty know he had returned safely from his three-year voyage to New Zealand, East Australia and Tahiti.
After that first voyage, Cook's ship was sold to a private individual and renamed the Lord Sandwich.
It was chartered to the British transport service to carry troops during the American Revolution, according to the Rhode Island Marine Archaeology Project.
The Atlantic reported that during a British navy attack in Narragansett Bay, the vessel was scuttled and used as a blockade to stop French ships, which had come to help the Americans, from reaching American shores.
The Rhode Island Marine Archaeology Project said researchers are working to confirm a fifth shipwreck site and determine which ship is located where. The group said the next phase "will require a more intense study of each vessel's structure and its related artifacts."
Researchers plan to make the announcement at 1o a.m. Wednesday at the Rhode Island Historical Preservation and Heritage Commission in Providence.