Sunken treasure ship found off Cádiz with 27 cannons and silver cargo

A remarkable underwater archaeological discovery in the Bay of Cádiz has revealed the remains of a 17th-century vessel carrying artillery and silver, shedding new light on smuggling networks and maritime trade in the Atlantic world.

Marine archaeologists have documented the recovery of 27 cannons and 18 silver ingots from a shipwreck uncovered during dredging works linked to Cádiz’s expanding container port. The site is considered one of the most significant underwater finds in Andalusian waters in recent years.

The investigation has been led by Ernesto Toboso Suárez and Josefa Martí Solano of the Centre for Underwater Archaeology at the Andalusian Institute of Historical Heritage, together with specialists from Gerión Arqueología. Their findings were presented at the First Ibero-American Congress of Nautical and Underwater Archaeology.

For now, the wreck has been given the provisional designation “Delta I” while researchers continue efforts to identify the vessel.

Analysis of the recovered artefacts suggests the ship was built in the Ibero-Atlantic tradition and operated in French service during the latter half of the 17th century.

The artillery cargo appears to have originated in Sweden and was likely purchased through Dutch intermediaries, reflecting the interconnected European arms trade of the period.

Archaeologists identified five distinct cannon calibres dating to the third quarter of the 1600s. Several pieces were heavily damaged, with some missing vital components such as muzzles and trunnions — the side fittings used to mount guns onto carriages.

Because no wooden gun carriages survived, researchers believe some cannons may already have been decommissioned before the ship sank and were being transported as ballast. Another possibility is that the damage occurred during combat or shortly before the wrecking event itself.

The site has also been affected by modern dredging operations, leaving many artefacts displaced from their original positions. Archaeologists describe the wreck as “decontextualised”, making it difficult to reconstruct the exact layout of the vessel on the seabed.

Alongside the artillery, divers recovered 18 silver ingots weighing approximately half a tonne. One ingot bears the date 1667, providing an important clue for dating both the cargo and the sinking.

Researchers suspect the silver formed part of an illegal smuggling operation.

During the 17th century, the Spanish Crown tightly regulated the movement of precious metals arriving from the Americas. Although Seville officially controlled Atlantic trade, Cádiz had become an increasingly important commercial hub thanks to its natural harbour and growing maritime activity.

These conditions encouraged widespread smuggling and unofficial trade routes that bypassed royal taxation and oversight. According to researchers, the discovery reinforces the view that foreign ships frequently participated in hidden commercial networks operating beyond Spanish control.

The combination of silver and weaponry aboard the same vessel also highlights the volatile nature of Atlantic commerce during an era marked by naval conflict, political rivalry, and competing economic interests across Europe.

The Bay of Cádiz contains some of Spain’s richest underwater archaeological heritage due to centuries of intense naval and trading activity. Recent port expansion projects have led to the discovery of several submerged wrecks, including Delta I, Delta II, and Delta III.

Experts believe the latest discovery could significantly improve understanding of maritime links between Spain, France, Sweden, and the Netherlands during the height of Atlantic trade.

The find may also provide fresh evidence about the illegal movement of silver and the routes used by European vessels operating around Cádiz.

For now, specialists continue cataloguing the recovered artefacts and analysing the ship’s remains in hopes of eventually determining the vessel’s identity and the circumstances surrounding its sinking.

The salvage actually occurred in July 2024 after the Port Authority of the Bay of Cádiz managed to uplift it from under the sea. Buried by sand and mud for centuries (depth of roughly six metres), the vessel needed four months of underwater work in technical and archaeological analysis of all kinds to be recovered safely. The final lifting in good weather and under tidal conditions was completed on 27 July.

Every step of the project was supervised by experts from the Andalusian regional government, underwater archaeologists and specialists in maritime heritage. Divers operated under extremely poor visibility while cleaning the sediments from the wreck to ready it for extraction. Engineers weighed the vessel and implemented a large supporting metal frame to stabilize it while being lifted.

After straps and flotation devices were used to secure the wreck, teams dragged up the body from below the seabed and carried it to Dock No. 5. Heavy cranes arrived to pick the remains up onto a specially prepared platform for detailed examination. Archaeologists began documenting every detail afterward through photography, 3D scanning, and thorough cataloguing techniques. Timbers on the ship were preserved under controlled humidity conditions before they, finally, are taken back to a protected underwater conservation area in the Bay of Cádiz.

Sources : Centre for Underwater Archaeology at the Andalusian Institute of Historical Heritage