GDANSK, Poland, June 22 (UPI) -- Polish archaeologists say they've discovered more than 40 18th-century cast-iron naval guns on the floor of the Baltic Sea off the Polish port of Ustka.
Researchers have recovered 12 of the cannon so far, with four of them undergoing conservation treatment, Poland.pl reported Wednesday.
"So far we had no such object in our collection," Iwona Pomian, head of the Undersea Research Division of the Central Maritime Museum in Gdansk, said.
"Discovered guns were manufactured in Sweden in 1772 and served as ballast of a ship," Pomian said.
A ship belonging to the Maritime Institute in Gdansk discovered the guns at a depth of 135 feet during seafloor scanning in connection with the planned building of an offshore wind farm.
The recovered guns have been sent to the Central Maritime Museum in Gdansk.