Ship Wrecked in Norway’s Deepest Lake 700 Years Ago Reveals its Secrets

A ship that sunk in Norway’s deepest lake several centuries ago has been identified as a føringsbåt, a type of boat that was used to haul cargo and passengers between 1300 and 1900 AD. These particular vessels were actually built specifically to cross Lake Mjøsa, Norway’s largest lake (73 miles or 117 kilometers long), and have been used for that purpose since medieval times.

The 33-foot (10-meter) medieval boat was first spotted on the bottom of the lake at a depth of approximately 1,300 feet (400 meters) in 2022. This was an accidental result of a sonar search undertaken by the Norwegian University of Science and Technology (NTNU) in Trondheim and the Norwegian Defence Research Establishment (FFI), which was designed to find munitions that had been dumped in the lake during World War II.

Unfortunately, the scientists responsible for this exciting discovery were only able to return to get a good look at the wreck this past October, which is why until now it had been considered a mystery ship.

When the wreck of this unknown ship was first discovered and explored, this was done through the use of an autonomous underwater vehicle that was in the possession of the Norwegian armed forces. This second time around researchers from the Norwegian University of Science and Technology deployed a similar vehicle, although this one was remotely operated by NTNU scientists who could direct it to wherever they liked.

Overhead view of Lake Mjøsa, Norway’s largest lake and the home of dozens of shipwrecks.(Kallera/CC BY-SA 4.0).

An Hour’s Worth of Discoveries, with Some Surprises

The efforts of the NTNU researchers to get an extended close-up look at the sunken boat were sabotaged by bad weather and technical difficulties. They had hoped to use the underwater vehicle to collect samples of the boat’s wood to allow for radiocarbon dating, but this was not possible.

Despite the limitations they faced, under the direction of NTNU maritime archaeologist Øyvind Ødegård the research team was able to spend approximately one hour examining the wrecked ship, and this was enough for them to learn a few things they didn’t know before.

For example, based on the boat’s specific characteristics, the researchers discovered that the vessel must have been constructed between 1300 and 1700. They were also able to identify it as a føringsbåt used to carry cargo and passengers back and forth across Lake Mjøsa, possibly for the purposes of trade. The lake represented a vital trade route dating as far back as the eighth century, when settlers were building communities along the shore of the 140-square-mile (360-square-kilometer) body of water, which is about 60 miles (100 kilometers) north of Oslo.

“We can see that it’s very well-preserved,” said NTNU maritime archaeologist Øyvind Ødegård, the leader of the underwater survey of the shipwreck, in an interview with Science Norway. “In freshwater, there aren’t organisms like shipworms that consume wood. But that also makes it difficult to determine its age, as assessing decay is challenging.”

Constructed specifically to travel across large lakes, the føringsbåt had flat bottoms that made it impossible for them to sail on the ocean. One other notable feature of the boat was the fact that it had an upright stern, which was a sailing innovation that wasn’t introduced in Norway until after 1300. Earlier Viking ships were the same in the front and in the back, highlighting how the designers of this post-Viking era vessel were deliberately attempting to separate themselves from Viking shipbuilding practices.

The researchers also saw clear indications that the sunken boat had a central rudder at the stern (the back) for steering, in contrast to Viking ships that used a steering oar on one side.

Underwater photograph of sunken boat from 2022, revealing its shape and characteristics. (FFI/NTNU).

One of the really interesting observations of Ødegård and his crew is that the wooden planks used to build the hull of the boat are wider than normal. This indicates they were cut with an ax rather than being cut up with a saw at a shipyard. This facet of the boat’s construction is significant, because it means the boat would have likely been built in the earlier part of that 1300 to 1700 window.

Adding further evidence to the latter conclusion is the boat’s immense depth of burial.

“Only parts of the hull and a stem are visible, and there’s a lot of sand and sediment covering the ship. So it must have been there quite a long time,” Ødegård concluded.

While the lake is noted for its calm waters, it does have strong currents in the area where the unknown ship went down. This may have been the reason why the føringsbåt didn’t survive turbulent waters, despite having been built to allow for smooth and convenient navigation of Lake Mjøsa.

“It’s not the calmest spot,” Ødegård said in an interview published by Live Science. “That leads us to guess that someone had an accident while crossing the lake.”

A Graveyard of Sunken Ships Awaits Exploration

Right now, the NTNU underwater archaeological team plans to return in the spring after the frozen lake has thawed, to relaunch the remote-controlled underwater vehicle again to more intently and deliberately examine the shipwreck. This will allow the researchers to confirm their identification of the sunken ship as a føringsbåt, and to perhaps get a close enough view to see what might have caused the ship to go down.

Researchers monitoring activities of underwater remote vehicle searching for wrecked boat in Lake Mjøsa. (FFI/NTNU).

Previous expeditions to the lake have produced evidence of about 20 shipwrecks located close enough to the shore of Lake Mjøsa to be reached by divers. This is notable, because it implies that in the deepest waters of the lake there must be an even larger number of shipwrecks waiting to be detected in those more treacherous zones.

Top image: Underwater photograph of sunken boat in Lake Mjøsa, with outline showing shape and characteristics.

Source: FFI/NTNU.

By Nathan Falde