In 1708, the British sank a Spanish galleon—a large war and/or merchant ship used from the 15th through the 17th centuries—off the coast of Colombia. Over three centuries later, its cargo of gold coins may have just helped scientists finally identify its wreck.

A team of researchers and naval officers used an uncrewed remotely operated underwater vehicle to study an 18th-century shipwreck that the Colombian government discovered in 2015. Their survey uncovered coins that provide further evidence the wreck is likely the long-lost San José Galleon, highlighting the usefulness of coins as chronological markers in marine archaeology.

“The Tierra Firme Fleet, commanded by the San José Galleon, held the exclusive monopoly on transporting royal treasures between South America and the Iberian Peninsula,” explained Daniela Vargas Ariza, lead author of the study published earlier this week in Antiquity, in a statement. Vargas Ariza is also an archaeologist affiliated with the Almirante Padilla Naval Cadet School and the Colombian Institute of Anthropology and History.

The fleet was one of the Hispanic Monarchy’s most important cargo fleets, according to the statement. Also known as the Catholic Monarchy, the crown ferried royal cargo from the Americas between the 16th and 18th centuries. That brings us back to 1708, when historical sources suggest that the British sank a cargo-heavy San José Galleon in Colombian waters.

Notably, the uncrewed vehicle captured high-resolution images of coins that had spilled onto the seafloor. Vargas Ariza and her colleagues used these images to reconstruct a 3D model, which allowed them to study the coins’ surfaces in more detail. This approach, along with other research, helped them reveal that the coins were minted in 1707 in Lima, Peru. That means the ship must have sunk after that year.

“Coins are crucial artefacts for dating and understanding material culture, particularly in shipwreck contexts,” the researchers wrote in the study. “These sites serve as invaluable repositories of historical information, especially when examining events related to the Tierra Firme Fleet,” they added. The “hand-struck, irregularly shaped coins” were the “primary currency in the Americas for more than two centuries.”

The coins showcase symbols associated with the crowns of Castile (the Spanish kingdom that united Spain in the late 15th, early 16th centuries) and Leon (a medieval Spanish kingdom that merged with Castile in 1230), further establishing the ship’s likely identity as a Spanish vessel. On the other side, they feature iconography related to Hercules and the Lima Mint. Furthermore, historical records link the coins to a 1707 treasure delivery from Peru, during which the San José Galleon met its tragic end.

“This body of evidence substantiates the identification of the wreck as the San José Galleon, a hypothesis that has been put forward since its initial discovery in 2015,” the writers concluded in the study.

The study ultimately establishes that, like pottery layers in archaeological excavations, coins serve as reliable reflections of a specific moment and culture in time.