While numerous other pirate harbors have previously been found along Norway's southern coast, historian Arne Flaatten said the recent discovery in the county of Telemark represents a rare and intriguing find, Aftenposten reported Wednesday.

"This is the oldest we've seen with a underwater wooden barricade to prevent alien ships (entering) the harbor," Flaatten said.

"This is the nicest harbor along the coast of Telemark," the local historian added.

Historians have tentatively dated the pirate harbor to the 18th century, when Denmark was allied with Norway.

The Norwegian newspaper said that historians believe that rich families in Norway would finance ships to fight against British and Swedish forces in the area.