The largest collection of antique shipwrecks ever found in Norway has been discovered under mud at the building site for a new highway tunnel in Oslo, the project's lead archaeologist said Friday.

Jostein Gundersen said at least nine wooden boats, the largest being 17 meters (56 feet) long, were found well preserved nearly 400 years after they sank at Bjoervika, an Oslo inlet near the new national opera house.

"For us, this is a sensation," he told The Associated Press."There has never been a find of so many boats and in such good condition at one site in Norway."