Shipwreck of 500-Year-Old Floating Castle Found to Contain 'Thrilling Haul'

The 500-year-old shipwreck of a medieval European king's personal "floating castle" has been found to contain a "thrilling" haul of exceptionally well-preserved plant materials—including exotic spices originating from the far-flung corners of the world.

Maritime archaeological excavations conducted at the wreck of the 115-foot-long vessel Gribshunden—once the flagship of the Danish monarch King Hans—have revealed a huge array of food items. Many were luxuries accessible only to the elite at the time. Researchers have described it as an "unprecedented" discovery.

Artist's illustration of a medieval ship
Stock image: Artist's illustration of a medieval ship. The Danish warship "Gribshunden" (not pictured) sank to the bottom of the Baltic Sea in 1495. iStock

The finds, documented in a study published in the journal PLOS ONE, provide a unique window into the lives of the northern European nobility in the late Middle Ages. These are the origins of today's truly globalized world.

The discovery includes extravagant artefacts that have rarely or never been seen before in an archaeological context.

Brendan Foley, an author of the study from the Department of Archaeology and Ancient History at Lund University, Sweden, told Newsweek: "This is perhaps the most thrilling haul of spices from a shipwreck because of its age, quality of the plant remains—exotic, expensive spices—and the remarkable state of preservation.

"Beyond shipwrecks, this is certainly among the most fabulous discoveries of spices in any archaeological context, on land or sea," Foley said.

King Hans's 'Floating Castle'

The royal Danish warship Gribshunden was built in 1485 and essentially served as the mobile seat of government for King Hans.

"Hans used this artillery-carrying warship to stitch together his widespread kingdom," Foley said. "It was quite literally his floating castle. Not just a warship, Gribshunden was an instrument of economic power, a social and cultural center, and also the focus of administrative and political functions of government."

The first generation of a new style of vessel, Gribshunden was characterized by a fusion of Mediterranean and northern European shipbuilding traditions. Replete with 11 iron cannons and room for 150 people onboard, the vessel was very similar to the ships sailed by 15th-century explorers such as Vasco da Gama and Christopher Columbus.

"It's our best look at what those ships must have been like," Foley said. "It's a well-preserved example of the enabling technologies that led to European domination of the planet after 1492."

But, despite its technological advances, the ship was struck by misfortune in 1495, sinking to its present watery grave in the Baltic Sea. The special circumstances of its last voyage add unique historical context to the latest findings.

Just before midsummer in June of that year, Gribshunden set sail from King Hans's capital of Copenhagen, Denmark, with the monarch onboard. The ship anchored off Stora Ekön (Great Oak Island)—located off the southeastern coast of what is now Sweden. Hans disembarked, likely accompanied by courtiers, noblemen and soldiers.

The king and his retinue were traveling to a political summit in Kalmar, Sweden, to negotiate with Sten Sture the Elder. Sture had effectively ruled Sweden since leading a successful rebellion against Danish-led forces in 1471. He wanted his state to break away from the Kalmar Union. This had joined the three Nordic kingdoms (Sweden, Denmark and Norway) together under a single monarch in 1397.

Hans was hoping that, through the negotiations, he could restore the union under Danish rule and convince the Swedes to accept his role as leader of the three kingdoms. In service of his goal, Hans wanted to impress the Swedish delegation, demonstrate the power and wealth of his kingdom, and discourage independence efforts.

Map showing location of the Gribshunden shipwreck
A map showing the location of the "Gribshunden" shipwreck off the coast of southeastern Sweden. The image also shows the main medieval towns along the Baltic coasts. Republished from Media Tryck, Lund University under a CC BY license, with permission from Frida Nilsson, original copyright 2022.

To do this, Hans carried with him "all manner of power displays: his warships, shipboard artillery, a battalion of professional soldiers, and small arms including crossbows and gunpowder weapons," the authors of the study wrote.

"Buttressing these hard-power elements were soft-power signifiers: coinage, artwork, splendid livery," not to mention exotic food delicacies. "Exotic spices were status markers among the aristocracy in Scandinavia and around the Baltic Sea during the Middle Ages," the study authors wrote.

But while the king was ashore, an explosion struck the ship. It burned down and sank to the bottom of the seabed, killing many of those who were still onboard. To make matters worse for Hans, when he finally made it to Kalmar, Sten Sture did not even turn up for the meeting, leaving the status of the union up in the air.

Exotic Spice Discoveries

The wreck of Gribshunden was rediscovered by sport scuba-divers in the 1960s and 1970s. Between 2000 and 2012, marine archaeologists recovered a number of artefacts during excavations. After a hiatus of several years, a new research initiative was launched in 2019, and explorations continued into 2020 and 2021.

Among the most notable finds from the dives in 2019—previously documented in a study published in the Journal of Archaeological Science: Reports, on which Foley was an author—is a wooden barrel containing the well-preserved remains of a butchered Atlantic sturgeon fish. This would have been highly valuable at the time as a food item.

Saffron from the Gribshunden shipwreck site
Saffron is pictured from the "Gribshunden" shipwreck site. Researchers said the spice still retained its distinctive aroma, even after 500 years below the sea. © 2023 Larsson, Foley/PLOS ONE

But nothing could have prepared the authors of the latest PLOS study for what they were going to find—a haul of exceptionally well-preserved plant materials, many from distant parts of the globe. They represented 40 species, including cereals, oilseeds, fruits, vegetables, spices and even a plant used for medicinal purposes.

Among the finds were plants consumed as flavorings (saffron, cloves, ginger, peppercorns, mustard, caraway, dill); others eaten as snacks or used in baking (almonds, hazelnuts, blackberries, raspberries, grapes, flax); and some that could be eaten as part of a meal (cucumber). The grapes could have been consumed as raisins, the authors wrote.

The plant remains were found in various forms, including seeds, fruits, nutshells, flower parts, and whole spices, the study shows.

Black pepper from the Gribshunden shipwreck
Black pepper from the "Gribshunden" shipwreck. A-C shows different views of the peppercorns, while D is an image of stalk segments, some with unripe pepper berries. © 2023 Larsson, Foley/PLOS ONE

"In the field, we knew that we had something special the moment the exotic spices appeared in the excavation," Foley said. "The saffron was obvious—nothing else looks like it. And we also could see peppercorns in the excavated material. We expected there would be more, but we needed the expertise of an excellent archaeobotanist.

"Fortunately, Mikael Larsson sits in the office one floor away from my office. He was willing to conduct the detailed analysis of the sediment samples we collected from the wreck."

Foley said there had been no indications previously that exotic spices would be found at the shipwreck.

Almonds from the Gribshunden shipwreck
Almonds from the "Gribshunden" shipwreck. A shows almond seed coats, while B is an image of nutshells. © 2023 Larsson, Foley/PLOS ONE

"[It was] completely unexpected, except that we have come to know we should always expect the unexpected with this shipwreck," Foley added. "The sturgeon find in 2019 was an indication that Gribshunden was carrying elite foods, but we didn't foresee the assortment and volume of spices we ultimately encountered."

The only non-edible plant that the researchers identified was henbane, which was used for medicinal and magical purposes at the time, and often associated with witchcraft.

In small doses, the plant—which has psychoactive properties—was used as a general analgesic. But, in larger doses, it was added as an ingredient in witches' ointment, as well as potions credited with magical, love-inducing powers. In sufficiently large quantities, henbane is highly poisonous.

The researchers found only one henbane seed on the ship. So, it is not clear if the plant was carried for medicinal purposes, or if it accidentally found its way into the other food supplies.

Cloves from the Gribshunden shipwreck
Cloves from the "Gribshunden" shipwreck. A-B shows clove flower buds while, in C, several stalks can be seen. © 2023 Larsson, Foley/PLOS ONE

Foley said the discovery of all the exotic species surprised the research team, with many of them having no archaeological precedent.

"Clove, saffron, ginger have never been found in excavations of medieval northern European sites," Foley added. "The volume of the spices was another surprise—we recovered more than 400 milliliters of saffron. That's an enormous amount, and would have been enormously expensive—it still is today."

The team found records of King Hans buying saffron in these volumes again and again—spending the equivalent of nearly a year's salary for a senior officer on Gribshunden just on the spice.

Larsson, the co-author of the study, said this is the first saffron discovery from an archaeological site anywhere in the world. "This is an unprecedented find," he told Newsweek.

Pieces of ginger from the Gribshunden shipwreck
Pieces of ginger from the "Gribshunden" shipwreck. The vessel was loaded with expensive plants and spices. © 2023 Larsson, Foley/PLOS ONE

The clove discoveries were "equally amazing," Foley said. "It grew in only one place in eastern Indonesia, very nearly the other side of the planet from Denmark and Sweden. It springs a host of questions about the trade and supply chain from the Moluccas [an archipelago in the east of Indonesia] to the Baltic."

The exceptional preservation state of the plant materials—some of which even feature fruit flesh and skin—can be explained by the peculiar environment of the Baltic Sea. It is characterized by low salinity and frigid temperatures.

"The saffron is amazing—it is still brightly colored, and it still smells like saffron, albeit with more than a hint of mud," Foley said.

The latest findings have a number of implications, according to the researchers, not least because they provide a clear look into the world of the elite in medieval northern Europe.

"We see that King Hans and his social circle not only consumed these expensive delicacies, Hans also used the spices to demonstrate his wealth and global connections," Foley said. "The consumption of large quantities of imported delicacies was one way Hans could use 'soft power' to convince the Swedes to accept his rule.

"We also see from these spices the beginnings of the first true period of globalization," he said. "Beginning in the late 1400s, the entire planet becomes connected in a way it never had been before. It's the launch of the modern world, and a lot of it is due to the new class of ships like Gribshunden. Goods are traded and people are communicating across previously unimaginable distances."