Sunken medieval warship continues to offer up its secrets

In 1495, the Danish warship Gribshunden sank off the coast of Sweden. In recent years, researchers have dived to explore the wreck and have made several important discoveries.

A new report by Rolf Warming and Johan Rönnby has just been released which details what was learned in 2023. Highlights include the discovery of a wooden war chest, analysis of mail armour, and a better understanding of the superstructure of the ship.


The Gribshunden (also known as Griffin or Griffin-Hound) was the flagship of King John I of Denmark (1481–1513), ruler of the Kalmar Union. In 1495 the ship was sailing to Kalmar with about a hundred German mercenaries onboard when a fire broke out causing the Gribshunden to sink. The wreck was discovered in the 1970s by recreational divers but not disclosed to researchers until the year 2000. Since then, it has proved to be a fascinating archaeological site that has offered much to our understanding of ships in the late Middle Ages.

Prof. Johan Rönnby (MARIS/Södertörn University) inspects and documents so-called standards, timbers belonging to the superstructure. Photo: Dr. Florian Huber

The latest fieldwork research on the wreck took place last May. With the help of underwater cameras and photogrammetric 3D technology, the research team led by Professor Johan Rönnby from Södertörn University and PhD candidate Rolf Warming from Stockholm University inspected and documented more parts of the ship’s remains.


By mapping timbers at the wreck site, the researchers have identified a large amount of the ship’s superstructure, which has been preserved even though the timbers are separated and scattered on the seabed. These timbers come from fore and aft castles – the ship’s fighting platforms. The timber can give researchers important insights into how the superstructure looked and thus the warship’s military capabilities.

One of the major finds during the latest dive was the exploration of a chest. By taking high-resolution photos of the object, they determined that it was a ‘weapon tool chest’ and were able to identify its contents.

Ammunition-making tool chest (Zeuglade in German) with contents. The solid line indicates the elongated side of the chest; the dotted lines indicate the estimated placement of its sides. Contents: (1) lead plates, (2-3) molds, (4) the chest’s elongated side along with iron corrosion (from the lock and fittings?), (5) cylindrical ‘cans’ (possibly powder containers), and (6) mold. Photo: Dr. Florian Huber, with outlines and notes by Rolf Warming.

The researchers write:

The contents of the chest are heavily corroded but appear to consist of several different objects located within a larger crust of corroded iron. In the crust, there are several sharp flint pieces, which may be interpreted as part of canister shot ammunition… In the northern half of the remains, it is possible to distinguish two elongated pieces of lead plate with some holes along the edge (presumably for easier handling during the casting process) and at least three stone molds for lead bullets of different calibers. The molds were intended for the production of bullets for handheld firearms, such as a handgonne, but also for larger caliber firearms, possibly arquebuses or smaller breech-loaded guns.

The chest and its contents probably belonged to the German mercenaries who were onboard when the Gribshunden sank. It is undoubtedly an important artefact related to medieval military technology.


Along with the diving work, a study was also carried out involving previously recovered fragments from mail shirts. With the help of Professor Kerstin Lidén of the Archaeological Research Laboratory (Stockholm University), the researchers discovered that the ring weave contained several different threads and construction techniques, indicating that it has been repaired on several occasions. Based on the dimensions of the preserved rings, such mail shirts (known as hauberks) may have contained up to 150,000 rings.

Decorative hem consisting of riveted brass rings for a mail shirt (hauberk) analyzed in connection with the dives. A mail shirt of this quality could have consisted of up to 150,000 rings. Photo: Rolf Warming.

This new research follows upon years of work on the Gribshunden. Previous dives led by prof. Johan Rönnby recovered an early firearm and a drinking tankard, and studies indicate that the ship was probably built in the southern Netherlands. The beautiful figurehead has also been raised from the sea floor and can now be viewed at Blekinge Museum in Sweden. As a result of these efforts by Professor Johan Rönnby (Södertörn University) and his collaboration partners, the wreck is now one of the most famous underwater cultural heritage sites in the world.

For Rolf Warming, whose PhD project is on Soldiers at Sea: Close Quarter Combat in the Fleets of Northern Europe, c.1450–1650 AD, being able to study the Gribshunden has been a one-in-a-lifetime opportunity. “Having worked on this wreck since 2015, it has been quite the adventure so far!” Warming tells “We learn something new not only with every fieldwork season but also with the ongoing research on the data and material from the wreck. It seems like an endless treasure trove of knowledge about Late Medieval life and the ships of that era – we look forward to continuing our research on this wreck!!”

Figurehead of Gribshunden after conservation, displayed at Blekinge Museum, Sweden. Photo: Brett Seymour / Wikimedia Commons

The report Gripen / Griphund (1495): Marinarkeologisk dokumentation av ett senmedeltida kravellskepp, by Rolf Warming and Johan Rönnby has been published in Swedish with an extensive English summary. Click here to read it.

Top Image: Prof. Johan Rönnby (MARIS/Södertörn University) and PhD student Rolf Warming (Center for Maritime Studies/Stockholm University) at the stern of the wreck where the standing floor timbers and the sternpost protrude from the seabed, seen from the starboard side. Photo: Dr. Florian Huber