Deep Beneath the Caribbean, Technology Unravels the Secrets and Controversies of the San José Galleon

“Hand-struck, irregularly shaped coins known as cobs in English and macuquinas in Spanish served as the primary currency in the Americas for more than two centuries,” said Daniela Vargas Ariza, lead researcher at Colombia’s Naval Cadet School Admiral Padilla, in a June 10, 2025, Antiquity study. The coins she wrote about, imaged by remotely operated vehicles (ROVs) almost 600 metres beneath the Caribbean, are now at the heart of verifying the identity of the San José galleon the self proclaimed “holy grail of shipwrecks” lost in 1708 with a cargo worth as much as £16 billion.

Image Credit to depositphotos.com

San José’s doom was met in the fading light of June 8, 1708, when a British squadron halted the Spanish treasure fleet off Baru Island, outside Cartagena. During the battle, a British cannonball set fire to the powder magazine on the galleon, consigning the ship and almost 600 lives to the ocean floor, along with an estimated 200 tons of gold, silver, and emeralds meant to pay for Spain’s war effort. For decades, the whereabouts of the ship remained unknown, its legend growing with each passing retelling.

Not until the arrival of high tech underwater technology did the San José start to reveal its secrets. In 2015, a joint mission between the Woods Hole Oceanographic Institution (WHOI), Maritime Archaeology Consultants, and the Colombian Navy sent an autonomous underwater vehicle (AUV) to sweep the seafloor off Baru Peninsula. Side scan sonar was used by the crew to map the seafloor, and they detected anomalies that were in turn investigated with ROVs and high definition cameras. These camera equipped ROVs descended to the wreck and took unprecedented photos of coins, porcelain, and cannons all lying amongst the coral encrusted timbers of the galleon over 600 meters down.

These non intrusive surveys, a signature of contemporary maritime archaeology, have transformed the discovery of shipwrecks. Using ROVs and AUVs, scientists can record vulnerable sites without disrupting their context, leaving both artefacts and the narratives they contain intact. High definition 3D reconstructions enable close analysis of objects in context, while side scan sonar and marine geophysical surveys aid in the location of wrecks buried beneath sediment.

The artefacts unearthed or more accurately, documented by the Colombian team tell a compelling tale. Most incriminating among them are the silver coins minted in 1707 at the Lima Mint, their irregular form and characteristic marks corresponding to colonial documentation of the San José’s contents. Digital zoom on the coins brought the Jerusalem Cross, Castile and León shields, and the Pillars of Hercules design motif, which was a trademark of the Lima mint. Chinese porcelain of the Kangxi era (1662–1722) and bronze cannons dated 1665 are additional evidence confirming the identity of the ship, matching manifests and period records. The researchers’ reports, published in Antiquity, assert “The finding of cobs created in 1707 at the Lima Mint points to a vessel navigating the Tierra Firme route in the early eighteenth century. The San José Galleon is the only ship that matches these characteristics.”

Carbon dating and archaeometric analysis have further tied the wreck to the early 18th century, organic remains and ceramics testifying to a chronology consistent with the San José’s last voyage. These kinds of multidisciplinary investigations integrating geophysical mapping, artefact analysis, and archival research have now become de rigueur in underwater archaeology, allowing identification to be based on firm scientific footing instead of guesswork.

But the San José’s rediscovery has not yielded closure, but rather kindled a furious ethical and legal struggle for control. Colombia, Spain, Peru, aboriginal groups, and the US based Sea Search Armada (SSA) claim it. SSA, previously Glocca Morra, asserts that it had found the wreckage in 1981 and is due half of its value by virtue of a pre-existing arrangement a point Colombia rejects, contending that the 2015 discovery was free standing and in another location (Business Insider). The government of Spain claims that under international sea law, the San José being a naval ship is still Spanish property, whereas Bolivian and Peruvian indigenous groups claim that the treasure was taken out of their territory by colonial means and hence is part of their cultural heritage (BBC).

The juridical framework of such shipwrecks, according to maritime law specialist Michail Risvas, “neither clear nor comprehensive.” The 2001 UNESCO Convention on the Protection of Underwater Cultural Heritage does offer rules for preservation and non commercial exploitation, but Colombia and the United States have not signed it. This puts the San José in a kind of legal purgatory, subject to rival claims and, perhaps, to commercial salvage or looting.

Historians and archaeologists, on the other hand, are calling for restraint. Most are of the opinion that the wreck be left alone, its importance lying in the fact that it is an archaeological site and a sea grave. “The treasure is part of the archaeological context, and as such has no commercial value. Its value is strictly scientific,” Colombian maritime archaeologist Juan Guillermo Martín declared, part of a building trend among archaeologists to preserve shipwrecks in place, rather than plunder them for profit.

The government of Colombia, meanwhile, has promised to construct a conservation laboratory and museum to house and conserve the San José’s artefacts, although auctions of certain items to finance rescue efforts have been controversial among cultural heritage stakeholders.

As the San José rests undisturbed in the Caribbean, it is both a technological wonder and a catalyst for global controversy. The saga continues to highlight how discoveries in underwater archaeology have not only shed light on the past, but also provoked deep questions regarding ownership, responsibility, and heritage in a globalized world.

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