The wreck of an extremely rare medieval sailing ship from the 13th century has been found in Sweden

Swedish archaeologists have discovered the wreck of an extremely old kogg – a large medieval merchant sailing vessel that was adapted for warfare. Ships of this type dominated the Baltic and North Seas between the 13th and 15th centuries.

Archaeologists have discovered an unknown wreck in the waters of the North Sea, next to Dyngö Island, near Fjällbacka, in southwest Sweden. Divers took samples for analysis which, when tested, gave a surprising result. It turned out that the oak trees used to build the kogg were felled in the first half of the 13th century.

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Thus, the unknown wreck turned out to be the oldest vessel ever found in Bohuslän – a historical land located on the Skagerrak Strait on Sweden’s west coast. Although the researchers made the discovery in September 2021, they waited to make the news public until researchers from the Department of Historical Studies at the University of Gothenburg had finished dating the tree rings from the wood samples collected by the divers.

We collected samples of wood to determine the age of the wreck by dating the year rings, the so-called dendrochronological analysis. It turned out that the wreck was built from oak trees felled between 1233 and 1240, so almost 800 years ago! – said Staffan von Arbin, a marine archaeologist at the University of Gothenburg.

Discovery

As the archaeologists themselves admitted, they came across the wreck of a medieval sailing ship somewhat by accident. The researchers from Gothenburg University were looking for shipwrecks along the coast of Bohuslän. They used a drone to film the area from the air. Off the coast of Dyngö Island they came across an object that piqued their interest and which they decided to investigate with the help of a dive team.

The wreck of a medieval sailing ship is located in a natural harbour. The drone footage showed a darker structure close to land at a depth of about 2m. The whole structure formed a stark contrast with the surrounding lighter seabed. When we decided to inspect the structure during the dive, it turned out to be the remains of a kogg-type vessel – explained von Arbin.

Archaeologists named the vessel ‘Dyngökoggen’, from a combination of the name of Dyngö Island and the type of sailing ship. The wreck search was part of von Arbin’s doctoral thesis on medieval shipping and the geography of transport. As emphasised by the person concerned himself, the search he conducted was for a completely different wreck.

We were looking for a shipwreck whose age is stated to be early 16th century, but instead we found a wreck from the first half of the 13th century. – von Arbin said.

The remains of the medieval kogg measured 10m long and about 5m wide. However, researchers believe that the ship could have been much larger and its length could have been as long as 20m. The first koggas appeared around the 10th century, but it was not until the 12th century that they began to dominate and displace other types of ships. Their reign on the waters of the Baltic and the North Sea lasted for another 300 years. The discovery of Swedish archaeologists has an extraordinary historical value, because not many wrecks from that period have survived to this day.

Sinking

Although it is not clear under what circumstances the vessel went down, archaeologists have their hypotheses. From the traces found, it is known that there was a large and intense fire on board. Since pirates were increasingly active on the southern coast of Norway, which at the time included Bohuslän, during the Middle Ages, it is not impossible that they attacked and sank the ship.

Another eventuality was participation in a naval battle. The first half of the 12th century was filled with internal disputes and battles for the Norwegian crown. It is therefore possible that a medieval sailing ship found near Dyngö Island became embroiled in a clash that ended its life.

What’s next?

Whatever the true cause of the kogga’s sinking, von Arbin and other researchers hope that the wreck can be thoroughly investigated in the near future. Unfortunately, apart from the bureaucratic issues, such a project requires a lot of money. At present, the problem is the lack of funds to start the research. However, due to the historical significance of the find, it is possible that this situation will change.

Photo: Staffan von Arbin / University of Gothenburg