A team of Norwegian researchers uncovered a maritime miracle while mapping a massive lake bed last month.

Archaeologists discovered a near-pristine shipwreck they believe to be up to 700 years old at the bottom of Norway’s largest lake, Mjøsa, during a government research mission.

The vessel, which is estimated to date back sometime between the 1300s and 1800s, was found nearly 1,350 feet below the surface, according to a Facebook post from the Norwegian Defence Research Establishment. Underwater images captured the 33-foot long ship in the lake’s depths.

Researchers stumbled upon the site while executing Mission Mjøsa, a government-funded project to map the 140-square mile lake bed. The body of water serves as a source of drinking water to about 100,000 people in the country, according to CNN, but the discovery of unexploded World War II munitions in the lake during previous inspections prompted a more expansive search into the water’s potential health risks.

Øyvind Ødegård, a maritime archaeologist at the Norwegian University of Science and Technology, told Live Science last month that he was expecting to find some hidden treasures beneath the surface when he signed on to the project, given the lake’s status as a vital trade route since the Viking era.

The vessel was in near-perfect condition due to a lack of wave activity in the freshwater lake, according to CNN. Ødegård told the outlet that some minimal wearing on the ship’s metal indicates the wreck has been on the bottom of the lake for a long time since corrosion takes hundreds of years to happen.

Archaeologists said the stern of the ship showed signs of having had a central rudder, which didn’t begin appearing on boats until the late 13th century. Using the evidence of light corrosion, as well as the rudder style, researchers narrowed down the ship’s possible era to no earlier than 1300 and no later than 1850, Ødegård told CNN.

Fuzzy, underwater photos of the boat show that the vessel is made of wood and was built with planks laid overlapped on top of one another — an old Norse technique used during the Viking age, according to Live Science.

Ødegård told CNN that the ship likely went down in bad weather since it was found in the middle of the lake.

Soon after researchers discovered the site, the weather turned and they were no longer able to investigate the wreck using camera equipment, Ødegård told media outlets. The team plans to return to the site next year once conditions improve.

Previous expeditions have uncovered some 20 shipwrecks in the lake’s shallow waters, according to The Smithsonian Magazine. But Mission Mjøsa is the first project to explore the lake’s greatest depths.