Two 18th-century cannons and a previously uncharted shipwreck have been discovered during work on Inishbofin harbour off north Connemara.
The finds are significant, according to Lar Dunne of Eachtra Archaeological Projects, who believes the unidentified ship traded in warm waters, possibly to the West Indies.
The cannons, which are not believed to have come from the wrecked ship, may date from the Jacobean or late Cromwellian period, he says. All of the finds are being conserved on the island for further research and their future will be determined by the National Museum of Ireland.
Archaeological monitoring of construction works at Inishbofin's harbour has been continuing since 2005, but little of significance was found in the channel area. When the project moved to the inner harbour, the "dynamic changed", Mr Dunne notes, and the shipwreck was discovered near Bun a tSruthain by one of his colleagues, Julianna O'Donoghue.
One side of the hull - built of oak and elm with a keel of yew - was in one piece, and several exposed timbers show evidence of intense timber infestation by the mollusc teredo navalis, a "shipworm" familiar to sub-tropical waters.
Excavation of the wreck took place during low spring tides and samples of oak were sent to Queens University Belfast for dating. However, as it was not Irish oak, the date has still not been determined, Mr Dunne says.
The iron cannons were found several weeks later on the east side of the old pier and are currently in temporary "wet storage" on the island. Island resident Joanne Elliott suggests that they could have come from the Kitty Brigg which sailed into the harbour in 1741, and the Britannia in 1780.
The Kitty Brigg was a merchant ship trading in the Caribbean and put into Inishbofin to take on stores. "Under cover of darkness, her anchor ropes were cut and she drifted onto the rocks. When the ship was certified to be helpless, she was looted," Ms Elliott says, and there is no record of what happened to the crew.
Almost 40 years later, the Britannia suffered "an even worse fate", she says, when it sought shelter in the island's harbour when blown off course during an Atlantic crossing.
On board was a complement of recruits for the British army, who had enlisted to fight north American colonists and who were bound from Newfoundland to Halifax or New York.
The captain altered course in bad weather for England, but the ship never made it and sank off the harbour. Those who survived received a less than welcome reception from some islanders at the time, she says, but the ship is very likely to have been carrying munitions.
Mr Dunne says that cannon balls or "shot" found on various parts of the island have been handed in to the archaeological team, but none so far matches the bore of the cannons.
It is also uncertain as to whether the cannon had any connection with the island's Cromwellian barracks.
He believes that the cannons may be French, but has sent details to an expert in England for further research.