When the shipwreck of the Santo Antonio de Tanna was discovered at the bottom of the old harbour of Mombasa by divers Conway Plough and Peter Philips in 1960, it set in motion, what was to be, perhaps, one of the largest excavation missions in Kenya’s maritime history.

When archaeologists from the Institute of Nautical Archaeology and the National Museums of Kenya excavated the 17th-century Portuguese vessel between 1976 and 1981 they recovered 40 M of its hull which was still intact. It was a remarkable find that is still talked of in Kenya. But what was the Santo Antonio de Tanná and why was its discovery so significant?

The Santo Antonio de Tanná was a 42-gun frigate that was built in 1678 in 2 places – Bassein and Goa. Construction work began in Bassein and was completed 2 years later in Goa, about 630 KM south of Bassein.

On the day, in November 1696, when she sailed to Mombasa as a flagship of a squadron delivering supplies and reinforcements under the command of Captain Domingos Pereira de Gusman, Fort Jesus (Fort São Jesus) was under siege from the Omani Arabs.

The squadron arrived on the Christmas of 1696 and began to offload her crucial cargo. In January 1697, Santo Antonio de Tanná lost some of her anchors and had to cruise back and forth while smaller vessels unloaded and transported the remaining cargo to the fort.

In April of the same year, Santo Antonio de Tanná sailed to Mozambique after accomplishing her mission in Mombasa. It was not long before she set sail again to Mombasa in response to a distress call from the Prince of Dau who was trying hard to keep off the persistent Omani attacks on Fort Jesus.

There are accounts of the frigate making a stop-over in Zanzibar to pick up more troops before proceeding to Mombasa. By September of 1697, the Santo Antonio was unloading her cargo and in the process, suffered several costly attacks that saw her lose most of her anchor cables.

Towards the end of October, while still unloading her cargo, the Santo Antonio de Tanná lost her last mooring lines. She had also suffered severe damage to her hull.

A decision by General Sampaio de Melo and a council of other officers finally ended Santo Antonio de Tanná’s seafaring career when it was decided that she had suffered extensive damage and was not seaworthy anymore. The team began to salvage Santo Antonio’s cargo and prepare to scuttle the frigate.

It is evident from the numerous artefacts collected onboard the relic of Santo Antonio de Tanná during her excavation that the General and his men did not manage to salvage the cargo on board. There is a possibility the frigate may have sunk while they were still trying to unload the remaining cargo.

One year later on December 1698, Fort São Jesus surrendered to the Omanis. At the time of its sinking, it is said the frigate had 50 bronze guns on board yet it started off from India with 42 guns. It is not clear when the additional guns were fitted.

As the National Museums of Kenya embarks on a study of shipwrecks on the waters of the Indian Ocean to inform a new initiative seeking to establish underwater museums in Kenya and preserve cultural heritage, the Santo Antonio de Tanná would be one piece of treasure they are sure to consider.

Special thanks to Tiago Miguel Fraga, whose Masters Thesis on the Santo Antonio de Tanná inspired and helped shape this story.