A survey of the biggest lake in Norway has revealed an almost perfectly preserved shipwreck, possibly from the Middle Ages. The 33-foot-long wooden ship is believed to have sunk between the 1300s and 1850 based on signs of a central rudder at what appears to be the ship's stern, a feature not seen before the late 13th century, and the corrosion of iron nails on either end of the ship, thought to have taken hundreds of years. Its overlapping planks represent a Norse shipbuilding technique known as clinker construction, which was used during the Viking Age, when the lake served as a busy trade route, per CNN. However, Viking ships were nearly identical on both ends, lacking a distinct bow and stern, per Smithsonian.
The wreck was discovered during a sonar scan on the lake, meant to map munitions dumped since World War II, which pose threats to the supply of drinking water for 100,000 people. "I assume that if we are going to find intact Iron Age or medieval vehicles in Norway, then [Lake Mjosa] would be the place to look, since it's big enough to have had its own distinct maritime history with a lot of seafaring and trade," principal investigator Oyvind Odegard of the Norwegian University of Science and Technology tells CNN. Plus "wooden shipwrecks can be very well preserved in fresh water, since they lack the organisms that usually eat wood that are found, for instance, in the ocean."
The ship rests at a depth of 1,350 feet in the middle of the lake, about 60 miles north of Oslo. Given its location, Odegard believes it may have gone down in a storm. He notes it likely had a square-shaped sail, which can be difficult to maneuver in very windy conditions. An attempt to record footage of the wreck was abandoned due to bad weather, though Odegard hopes to get a better look next year. "If we are lucky, there could be some cargo on board," he tells Live Science. In the meantime, researchers will continue mapping the depths of the lake. They've covered just 15 square miles of the 140-square-mile lake so far. Odegard expects more shipwrecks will be uncovered. "We could find vessels from since the beginning of human activity in the area," he tells CNN. (Read more shipwreck stories.)