Severe winter storms over the last two years are believed to have led to the recent discovery of relics from the Spanish Armada off the Irish coast.
Cannons from the merchant vessel, La Juliana, have been found in the sands off Streedagh, County Sligo.
Timbers from the exposed wreck began washing ashore in April.
The guns date back to 1588, but are said to be in excellent condition. Two have been taken off the seabed.
One bears a dedication to St Matrona, a saint particularly venerated by the people of Catalonia and Barcelona.
It is dated 1570, the year in which La Juliana was built, putting the identity of the ship beyond doubt, the Irish government has said.
Heather Humphreys, minister for arts, heritage and the gaeltacht, has visited the wreck site.
"We have uncovered a wealth of fascinating and highly significant material, which is more than 425 years old," she said.
"This material is obviously very historically and archaeologically significant."
Two other vessels from the Armada sank nearby in violent storms in September 1588.
More than 1,000 soldiers and mariners drowned when the La Lavia and Santa Maria de Vision went down.
La Juliana traded between Spain and Italy until King Philip II commandeered it for the Armada fleet of 130 ships to invade England and take Queen Elizabeth I's throne.
The boat weighed 860 tons, carried 32 guns, 325 soldiers and had a crew of 70.
A security operation is in place to safeguard the valuable shipwreck site from treasure hunters.