Dive Into the Ocean Archive

The Ocean Archive is a new digital platform that enables exploration of Denmark’s maritime history in an entirely new way. Users can search across thousands of ship journals, locate specific voyages, and track ship routes on a map based on historical positional data.

Simultaneously, the platform provides access to systematically extracted climate data such as wind and weather conditions, making it possible to analyze the development of past climates over time. The initiative is led by the Danish National Archives (Rigsarkivet) and the Danish Meteorological Institute (DMI), and the project is supported by the A.P. Møller Fonden.

The Ocean Archive opens a digital window to vast quantities of sources relevant to climate history, maritime history, and genealogical research. The platform consolidates data on sailing routes, weather observations, and dramatic events at sea—and makes them readily accessible to both researchers and the public.

For example, one can find answers to questions such as: What occurred during the historic storm at the Battle of Køge Bay in 1710, and how did emigrants sail with the Thingvalla Line to New York when over 300,000 Danes emigrated to the United States in the 18th and 19th centuries?

Since 1675, Danish captains and first mates have been required to maintain ship journals. Today, thousands of these are stored in the Danish National Archives and are gradually being made available online.

Leah Porse Rasmussen, archivist at the National Archives of Denmark, states:

“We have looked forward to opening up maritime history in a new way, making it easier for everyone to delve into Denmark’s maritime past and trace their ancestors via the waterways.“

Although ships’ journals today constitute an important source for climate data and navigation, they originally served an entirely different purpose. The journals were maintained for legal and administrative reasons—to document voyages, cargo, and onboard incidents so that responsibility could be assigned. This function remains valid today, as logbooks continue to be mandatory in maritime operations.

Precisely for this reason, ships’ journals serve as a strong example of how historical sources can acquire new significance: Created for control and accountability, they are now central to research on climate, history, and human lives at sea.

With the Ocean Archive, ships’ journals are not merely made accessible—they become an active instrument in the work of understanding the past. The journals contain highly precise, contemporary records of time, position, and weather conditions, day by day and hour by hour. This means that in many cases one can come very close to historical events: If a Danish ship was in the vicinity, its observations can provide concrete and independent insight into what actually occurred—at sea and in the world around it.

Ulrik Smith Korsholm, Deputy Director and Chief Scientist at DMI, is curious about his family history and looks forward to uncovering more interesting stories:

“First and foremost, the Ocean Archive contributes important knowledge to climate research. As an amateur genealogist, I am particularly excited to delve into this treasure trove of information from earlier times.”