Marine archaeologists have confirmed that two shipwrecks off Costa Rica’s southern Caribbean coast are the remains of long-lost Danish slave ships — a discovery that restores a key chapter in Afro-Costa Rican heritage more than 300 years after the ships’ arrival.
The wrecks lie off the coast of Cahuita National Park and were long believed to be pirate vessels due to their fragmented condition. Local fishers, who settled in the area in 1826, assumed the ships sank during a sea battle. But in 2015, the discovery of unusual yellow bricks raised new questions about the ships’ origins.
The bricks matched those produced in Flensburg, Germany, for use in Denmark and its colonies during the 18th and 19th centuries. That, combined with historical records of two Danish slave ships wrecked in Central America in 1710 — the Fridericus Quartus, which was burned, and the Christianus Quintus, which broke anchor and drifted away — prompted a new investigation.
In 2023, Danish researchers from the National Museum and the Viking Ship Museum carried out underwater excavations. They recovered charred timber, clay pipes, and additional yellow bricks. Laboratory analysis confirmed the wood came from trees felled between 1690 and 1695 in the Baltic region. The clay in the bricks originated in southern Denmark, consistent with 18th-century Danish brickmaking. The pipes matched Danish styles from just before 1710.
“These findings are conclusive. There is no doubt these are the two missing Danish slave ships,” said marine archaeologist Prof. David Gregory of the National Museum of Denmark. “The bricks, the timber, the fire damage — it all aligns with the historical accounts.”
Rebellion and mutiny
The ships’ journey from Copenhagen to West Africa, and eventually to Costa Rica, was fraught with disaster. According to Danish archives, a rebellion broke out aboard the Fridericus Quartus during its voyage from Ghana to the Dutch colony of St. Thomas. The growing threat of war and navigational errors led the captains to divert toward Costa Rica. On March 2, the ships ran aground near the southern Costa Rican district of Cahuita.
Fear of attack from pirates and local tribes caused infighting among the crew. A mutiny followed, involving both the sailors and the enslaved people. Around 650 survivors remained on the beach.
“This is one of the most dramatic events in Denmark’s maritime history — and now we know where it happened,” said marine archaeologist Andreas Kallmeyer Bloch. “This discovery fills in two major gaps in Danish history.”