Two centuries-old shipwrecks, long presumed to be the remains of pirate vessels, have now been definitively identified as 18th-century Danish slave ships.
Resting in the shallow waters near Cahuita National Park on Costa Rica’s southern Caribbean coast, the wrecks of the Fridericus Quartus and Christianus Quintus rewrite a chapter in both local folklore and European maritime history. Far from legends of treasure or pirate battles, these shipwrecks reveal a grim narrative of transatlantic slavery, fire, and failed rebellion.
According to Archaeology Magazine, new underwater excavations and material analyses provide conclusive evidence linking the vessels to Denmark’s colonial slave trade in 1710.
From Pirate Shipwrecks to Slave Ships : A New Chapter in Denmark’s Maritime Past
The wrecks were long misidentified as pirate ships, largely due to their fragmented state and local legend. But in 2023, after years of underwater excavation led by the National Museum of Denmark, the truth surfaced.
The two vessels, part of the Danish West India Company, vanished in 1710 during a failed slave transport from Ghana to the Danish West Indies—now the U.S. Virgin Islands (St. Thomas, St. Jan, St. Croix).
The breakthrough came in 2015, when yellow bricks were discovered near one of the wrecks by American marine archaeologists.
These bricks, made from Danish clay and produced exclusively in Iller Strand and Egernsund—both sites near Flensburg Fjord—were identified as Flensburg bricks, a key marker of 18th-century Danish architecture.
Rebellion and Desperation on the Atlantic Crossing
According to archival documents, as the Fridericus Quartus prepared to depart the Gold Coast, a violent rebellion erupted. Enslaved people broke free from their shackles but were brutally repressed. The leader of the revolt was captured, had his hands cut off, and was decapitated as punishment.
Fearing more uprisings, the Christianus Quintus was ordered to accompany its sister ship across the Atlantic.
Their journey, already fraught with tension, turned catastrophic. The ships lost their bearings, and as provisions ran dangerously low, a mutiny loomed. To stave off starvation, the captains chose to release hundreds of enslaved people, hoping to stretch dwindling food supplies. An estimated 600 of them eventually reached Costa Rica’s shores. Not long after, the Fridericus Quartus caught fire, while the Christianus Quintus, having lost its anchor, was driven into the coastal surf and shattered by the waves.
Dendrochronology and Fire-Damaged Baltic Oak Confirm the Identity
Marine archaeologists from Denmark and Costa Rica retrieved oak timbers, bricks, and Dutch-made clay pipes from the wrecks. Analysis confirmed the wood came from Schleswig-Holstein, Scania, or Denmark, and was felled between 1690 and 1695, using dendrochronological dating. The timbers were charred and blackened, aligning with historical records of the Fridericus Quartus catching fire.
Dutch clay pipes, common among Danish sailors but rarely used more than five years, were also found among the wreckage. Combined with the bricks, they were decisive in confirming the ships’ origins.
“The analyses are very convincing, and we no longer have any doubts that these are the wrecks of the two Danish slave ships,” said David Gregory, marine archaeologist and research professor at the National Museum of Denmark.
“The bricks are Danish, and the same goes for the timbers, which are additionally charred and sooty from a fire. This fits perfectly with the historical accounts stating that one of the ships burned.”
Uncovering Denmark’s Role in the Transatlantic Slave Trade
Although Denmark’s participation in the transatlantic slave trade was smaller than that of Britain or Portugal, it was far from negligible. Between the 17th and 18th centuries, the Danish West India Company transported over 120,000 enslaved Africans to the Caribbean and Europe. The ships were bound for the Danish colony of St. Thomas, central to this commerce. These two vessels—now lying silent on the seabed—are stark reminders of that dark legacy.
The project was conducted under Njord, the National Museum of Denmark’s global maritime research initiative. It involved collaboration with the Viking Ship Museum, the University of Southern Denmark, the National Museum of Costa Rica, and the NGO Centro Comunitario de Buceo Embajadores y Embajadoras del Mar. The rediscovery of the wrecks carries profound significance not only for Danish history, but for the local communities in Cahuita, who have lived beside these ruins without knowing their origin.
“It’s been a long process, and I’ve come close to giving up along the way,” said Andreas Kallmeyer Bloch, marine archaeologist and museum curator at the National Museum of Denmark, who co-led the excavation.
“But this is undoubtedly the craziest archaeological excavation I’ve yet been part of. Not only because it matters greatly to the local population, but also because it’s one of the most dramatic shipwrecks in the history of Denmark, and now we know exactly where it happened.”
