Sea voyages from Denmark to Norway may have been possible across open waters, though sticking to the coastline was likely the safer route.
People living in Bronze Age Denmark may have been capable of traveling directly across the open sea to Norway, according to a study published on April 2, 2025, in the open-access journal PLOS ONE by Boel Bengtsson of the University of Gothenburg, Sweden, and colleagues. To support their research, the team developed a new computer modeling tool designed to help scientists better understand ancient maritime travel.
The Bronze Age societies of present-day northern Denmark and southwestern Norway share striking cultural similarities, including comparable artifacts, burial customs, and architectural styles. Traditionally, scholars have attributed these connections to seafaring along a coastal route, roughly 700 kilometers long, that winds across Denmark, up the Swedish coast, and back down to Norway. However, the researchers behind this new study propose that people may have also taken a more direct route: sailing over 100 kilometers of open sea, which could explain the close cultural ties between the two regions.
A New Modeling Tool for Ancient Seafaring
To study this possibility, the research team developed a modeling program that uses data on environmental factors like currents and wind, along with data on how a vessel moves through the water, to simulate different trips. For this study, the team simulated trips using a reconstruction of the Hjortspring boat, a large paddle-driven canoe from around 350 BCE.
According to their simulations, Bronze Age people may have had the capability to travel directly from Denmark to Norway over the open ocean, though these trips likely would have required a boat able to navigate in waves up to one meter high and winds up to 10 knots, along with good weather forecasting and navigational skills. These open-sea voyages may also have been limited to the summer months. In contrast, following the longer route between the two sites along the coastline was likely safer and possible all year, but probably would have taken multiple weeks to complete and required frequent stops to restock supplies.
In addition to these insights into Bronze Age Scandinavian crossings, the authors note that their model could be adapted to study seafaring for any vessel with sufficient information about its hull shape and specifications.
The authors add: “These new agent-based simulations, applied with boat performance data of a Scandinavian Bronze Age type boat, demonstrate regular open sea crossings of the Skagerrak, including some 50 km of no visible land, likely commenced by 2300 BC, as indicated by archaeological evidence.”
Reference: “Seafaring and navigation in the Nordic Bronze Age: The application of an ocean voyage tool and boat performance data for comparing direct open water crossings with sheltered coastal routes” by Boel Bengtsson, Alvaro Montenegro, Ashely Green, Matteo Tomasini, Martyn Prince, Victor Wåhlstrand Skärström, Knut Ivar Austvoll, Johan Ling and Cecilia Lindhé, 2 April 2025, PLOS ONE.
DOI: 10.1371/journal.pone.0320791
This work is supported by Riksbankens Jubileumsfond under Grant M21-0018.
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