What they found in this 300-year-old sunken ship left archaeologists speechless

A 300-year-old shipwreck off Madagascar is turning a legendary pirate raid into a matter of record. Researchers now say the remains fit with a Portuguese warship that was captured in 1721 during the high tide of Indian Ocean piracy.

The ship, Nossa Senhora do Cabo, sailed from Goa bound for Lisbon, with wealth and officials on board. Its story now steps out of rumor and into evidence, with context that is as human as it is historical.

The Cabo carried diplomatic cargo, religious objects, and elite goods that were to be transported along the Indo-Atlantic trade route. The haul has been valued at about 138 million dollars in today’s money.

Brandon A. Clifford of the Center for Historic Shipwreck Preservation led the multi-year effort to tie this wreck to the historical record. His team worked with archives, hull measurements, and artifacts to build a case.

History of this pirate shipwreck

The wreck lies in a sheltered harbor at Nosy Boraha, an island off Madagascar’s eastern coast.

This small island was previously called Île Sainte-Marie, and pirates were known to steer captured prizes here to refit and split spoils. The Cabo appears to have been one of them.

Historical accounts place the capture near Réunion in April 1721, after storms crippled the ship’s defenses.

Pirates towed the prize roughly 400 miles (645 kilometers) to the west, then dumped the vessel once its cargo was stripped.

Pirate shipwrecks litter the harbor

More than 3,300 artifacts have been cataloged from the site, and “at least four pirate shipwrecks or their prizes lie in the harbor itself,” said Clifford.

Overlying silt and sand now limit further recovery, so investigators work with what careful seasons have already revealed.

Among the finds are gold coins with Arabic inscriptions, Chinese export porcelain, and Catholic devotional art.

A small ivory plaque inscribed with INRI in gold letters stands out as a direct link to Christian liturgical objects that were carried by church leaders.

How they identified the shipwreck

A new study lays out why this site matches the Cabo rather than any of the neighboring wrecks at the bottom of the harbor.

The list includes the style and spread of the cargo, the timber layout in surviving frames, and a cluster of coin dates that end before the ship’s loss.

The hull elements and fittings align with a Portuguese East Indiaman, built in Asia and strengthened for long ocean legs.

That profile fits the description of a government convoy ship departing Goa with high-born passengers and sacred items.

People at the center of the story

Primary sources record the outgoing Portuguese viceroy aboard, alongside the Archbishop of Goa.

Records also note that about 200 enslaved people from Mozambique were below decks, a hard truth that anchors this history in human cost.

The viceroy was later ransomed, but the fates of the archbishop and the enslaved remain uncertain. Archaeology can name objects and timbers, yet details of some lives remain out of reach.

Historians trace how European pirate settlers and local leaders intertwined along Madagascar’s east coast, especially here. That political crossover shaped the Betsimisaraka kingdom, according to a landmark study.

Sheltered anchorage, access to shipping lanes, and little colonial oversight made Sainte-Marie practical for illicit trade. That mix also left the seabed layered with overlapping wreck sites that now complicate excavation.

What the evidence shows

The artifact set is consistent with a Goa-to-Lisbon route serving elite patrons. Porcelain from Jingdezhen, Indo-Portuguese religious carvings, and mixed coinage sketch a clear trade footprint.

Hull remains show heavy frames and ocean-ready construction, features that would be expected for a large convoy ship carrying valuables.

Geophysical maps add a site outline that matches a big hull buried under ballast and coral growth.

Teams plan conservation and selective recovery rather than wholesale digging, given the fragile conditions of the shipwreck.

Provenance work on the devotional objects may link them to church inventories in Goa or Réunion.

Field seasons have been careful and incremental, and patience is part of the method. The harbor holds multiple wrecks, so separating their stories requires tight mapping and conservative sampling.

This identification ties a global trade network to a specific harbor and moment in time. It shows how colonial wealth, piracy, and faith objects moved together on the same decks.

It also asks readers to face the full passenger list, not just the treasure chests. The enslaved, whose names were not recorded, are part of the site’s record too, even though no documents can attest to any specific details.

The study is published in Wreckwatch.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–