Wreck from 500 years ago with valuable load of osmium found in the Baltic Sea

Swedish archaeologists have examined a 500-year-old wreck in the Baltic Sea with a cargo of osmium. The extremely unique find unlocks the secrets of Swedish history.

In the Baltic Sea, north of Dalarö located in the Stockholm Archipelago, at a depth of just 28 metres, archaeologists from Sweden have discovered a unique treasure from the region’s commercial past. On a wooden wreck, researchers located a large cargo of a special iron called osmium.

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According to the findings of scientists from the VRAK Museum, the vessel they are investigating dates back to the mid-16th century. Not the first and certainly not the last one that archaeologists have discovered in the waters of the Baltic Sea. It is precisely the peculiarity of this body of water that today we have the opportunity to gain insight into the history of 200, 300 or even 500 years ago.

A copper pot is still stuck in the brick fireplace. There are also ropes, as thick as a grown man’s forearm, which are almost intact. These organic things cannot be found on land, because they have long since rotted away – Jim Hansson, project manager and marine archaeologist, describes the underwater discovery.

The conditions in the Baltic Sea create a unique mixture. It has allowed many wooden ships and vessels with their cargoes to be preserved almost unchanged until our times. And with today’s possibilities to explore, research and document these finds, we have a real chance to not only get to know their historybut also to preserve it for future generations.

High-quality photographs, films or 3D models created by means of photogrammetry are tools that until recently could only be dreamt of. Objects captured by these means will forever remain preserved in an unchanged form. They will also contribute to many studies without the need for diving and will make it possible to follow the process of degradation of individual wrecks over the years.

None of my professional colleagues, both in Sweden and abroad, have ever seen such a well-preserved ship – said Jim Hansson.

Osmund

Osmunds are pieces of iron weighing around 300 grams. At first glance, they may not seem particularly valuable or exciting like warships full of guns or galleons with gold and jewels. However, as it turns out, for some, Osmund iron is worth much more than gold.

Although it has been an important commodity for centuries, very little of it survives in Sweden. According to available information, a total of perhaps half a barrel could be collected. However, the wreck under investigation has already yielded around twenty barrels, and there is still potential for more.

The Osmund was an important export commodity for Sweden. However, archaeologists discovered something else on the wreck. As it turned out, iron bars were also among the cargo carried. These were a type of more refined iron, which began to replace osmund in the 16th century.

The Baltic Sea is a combination of not too salty water, low temperatures, darkness, lack of ship’s augers and low oxygen content, which means that much material can be preserved in almost perfect condition. The grotmast on the wreck is still standing and waiting for divers at around ten metres depth.

In addition to the osmium, there are barrels in the hold where butter has probably been found, fish remains and elk or deer horns. In the cabin, on the other hand, there are personal belongings of the sailors, such as shoes and small objects that give a glimpse of life on board and what Swedish exports were like more than 500 years ago.

Unknown unit

As it turns out, it is not only the contents of the hold that arouse emotions. The wreck itself is also a rather unusual and mysterious discovery. The researchers do not know what type of ship it is, as they have never come across a similar vessel before.

The specialists managed to establish that the ship was built from pine, which originated in eastern Sweden and was felled in the 1540s. The researchers also discovered that at some point the ship was repaired with pine from Finland. The barrels that the divers discovered on board, on the other hand, came from the Baltic countries and, like the ship, were made in the 1540s.

Unfortunately, the cause of the ship’s sinking has not yet been established. Perhaps the vessel began to take on water? Maybe it happened during a storm as a result of the sudden movement of a heavy cargo? Today we can only speculate. What is certain is that it happened in a flash. According to estimates, the iron itself, which was the cargo, weighs about 8-9 tonnes.

A shadow of hope is offered by archaeologists finding trademarks that may lead to the owner of the cargo. No doubt this would provide more information about the ship. And who knows? Maybe even establish the name of the vessel. So far, researchers have found three lids with the same marking. However, it is not known whether this is a trademark, a trade name or something else.

Stolen monuments

This unusual wreck was accidentally discovered in 2017 by a diver who was looking for the wreck of another vessel. However, it took some time before researchers tackled the wreck with more interest. Unfortunately, in the meantime, the wreck was discovered by looters, who took several artefacts from it in the first half of 2019.

According to project manager Jim Hansson, these were most likely foreign divers who noticed the archaeologists’ activities in the area. Fortunately, the wreck now has much better protection. The area where it rests on the bottom is under the special care of the Swedish Coast Guard.