For more than a century, the Hjortspring boat has carried a lingering mystery. The 2,400-year-old war canoe — discovered on the Danish island of Als and intentionally sunk after an attack involving roughly 80 warriors — offered extraordinary preservation, yet one crucial question remained unanswered: where did it come from?
An analysis of the vessel’s caulking and cordage has produced the strongest clue yet. The study, published in PLOS One, found that the waterproofing was made from animal fat mixed with pine pitch — a chemical signature that points toward pine-rich regions along the Baltic Sea rather than Denmark itself. Also uncovered: a partial human fingerprint pressed into the caulking — which could offer an even more direct link to the warriors who once occupied the vessel.
“The Hjortspring boat is the only prehistoric plank boat that has been found in Scandinavia,” says Mikael Fauvelle, an associate professor and researcher in the Department of Archaeology and Ancient History at Lund University. “Because the Hjortspring boat was purposefully sunk in a bog as an offering it was preserved in the unique low oxygen environment for over [2,000] years, making it the only preserved example of one of these boats that we have.”
Clues in the Caulking Reveal a Baltic Origin
Radiocarbon dating of the materials associated with the vessel returned a range of 381 B.C.E. to 161 B.C.E., placing its construction firmly within the pre-Roman Iron Age and aligning with earlier estimates from the site.
Dated Bronze Age art, early Iron Age art from Brastad, and comparison of Hjortspring boat.
(Image Credit: 3D model by Richard Potter; Fauvelle et al., 2025, PLOS One, CC-BY 4.0)
While the chemical signature of the caulking points strongly toward regions east of Denmark, the researchers note that pine pitch could theoretically have reached the area through trade. But if the boat itself originated along the Baltic coast, reaching Als would have required a long open-water voyage — a journey that suggests careful planning, coordination, and intent.
“This means that the crew of the boat traveled 100s of kilometers by sea to launch their attack on Als in southern Denmark,” says Fauvelle. “While we will never know exactly what drove around 80 warriors to attack Als some 2,400 years ago, these findings suggest it was an inter-regional conflict that involved substantial planning and logistical capacities."
Fauvelle adds, "such long-distance maritime raiding is quite similar to what we see in the much later Viking period […]. Our findings suggest that this pattern of long-distance maritime trading and raiding might have characterized Scandinavian societies for thousands of years.”
On left: Caulking fragment of fingerprint; On right: High-resolution x-ray tomography scan of fingerprint.
(Image Credit: Photography by Erik Johansson, 3D model by Sahel Ganji; Fauvelle et al., 2025, PLOS One, CC-BY 4.0)
The team’s identification of a fingerprint in the caulking adds a rare human detail to this broader picture — a small but tangible connection to one of the people responsible for maintaining the vessel during its working life.
Read More: The 3,000-Year-Old Uluburun Shipwreck Reveals Ancient Trade Routes
A Century-Old Mystery Edges Closer to Resolution
First excavated in the early 20th century, the Hjortspring boat has long puzzled researchers because the weapons and shields found with it were common across northern Europe, offering no clues about where its crew originated. The team now hopes to extract ancient DNA from the caulking — including from the fingerprint — which could offer an even more direct link to the people who once used the vessel.
Fauvelle says the findings point to two broader insights. The first is that long-distance travel and conflict were already part of life in the early Iron Age, showing that ancient Scandinavian societies were socially and politically complex.
The second is how much archaeological science has advanced: modern techniques now allow researchers to study the boat in ways that would have been impossible for the original excavators a century ago, opening the door to even more discoveries as these methods continue to develop.
Read More: Ancient Shipwreck Cargo Sheds Light on Iron Age Trade And a Lost Mediterranean Seaport
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from the recent study published in PLOS One: New investigations of the Hjortspring boat: Dating and analysis of the cordage and caulking materials used in a pre-Roman iron age plank boat
