Treasures lost to the sea 280yrs ago in shipwreck hav e been restored to pristine condition (Picture: Historic England)

A treasure trove of silver, swords and knives that sank to the bottom of the sea in 1740 have been painstakingly recovered and preserved in a project led by Historic England.

Using a variety of scientific techniques, more than 2,500 artefacts have been recovered from the wreck of the Rooswijk, including etched sabre blades, carved knife handles, silver coins, thimbles, a nit comb and more.

These discoveries are the result of two excavations carried out in 2017 and 2018, in partnership with the Cultural Heritage Agency of the Netherlands to recover artefacts from the Rooswijk.

A film documenting the find showcases how the artefacts were recovered and investigated by specialists at Historic England’s Research Facility in Portsmouth. It also highlights various techniques that can help scientists to analyse finds like these.

‘It has been fascinating to slowly reveal the many secrets hidden for hundreds of years within the objects found at the Rooswijk wreck site,’ said Angela Middleton, senior archaeological conservator, at Historic England.

Chests containing trade goods, such as sabre blades, were recovered from the Rooswijk, but covered in thick layers of seabed concretion.

A concretion is a material that builds up under the sea made up of shells, stones and other nearby artefacts. Specialists meticulously removed these layers using several techniques, including a tool known as the ‘Air Scribe’, which eliminates small layers of concretion from around the blades.

This revealed that the blades were etched on both sides, with some displaying a Sun, Moon, stars, and a weaving snake. The etchings were found to be created with acid, as this was a cheaper alternative to engraving. 

The designs on the blades were not related to the Dutch East India Company but were more link those seen on other bladed weapons across Europe, Africa, and the Middle East. 

X-rays have been used to see inside concreted marine artefacts. This technique, which involves taking images of the inside of an object, has revealed silver coins, knife blades, and tool handles that have been hidden away since 1740.

The team revealed that 1,846 silver coins were recovered from the Rooswijk shipwreck.

These coins can be divided into two categories: official and private. The official coins were company owned and primarily used for trade and exchange. The private coins were likely owned by crew members who intended to make a profit for themselves on voyages. 

The team revealed that 1,846 silver coins were recovered from the Rooswijk shipwreck (Picture: The Historic England Archive)

The blades were etched on both sides, with some displaying a sun, moon, stars, and a weaving snake (Picture: The Historic England Archive)

The designs on the blades were not related to the Dutch East India Company but were more link those seen on other bladed weapons across Europe, Africa, and the Middle East (Picture: The Historic England Archive)

It is possible that up to half the silver onboard the Rooswijk was illegal. While smuggling silver coins was officially prohibited by the Dutch East India Company, the findings show that it seems to have been common practice by many on the Rooswijk. 

Many of the coins did not originate from the Netherlands – those being officially transported bear the letter ‘M’, meaning they were made at the Mexico City Mint.

The Rooswijk was a Dutch East India Company vessel that sank on the treacherous Goodwin Sands in 1740.

The ship departed from Texel in the Netherlands and hit a fierce storm on its way to Batavia (modern-day Jakarta), causing it to sink. The ship sank with all 237 members of its crew, trade goods, and personal belongings.

It became a Protected Wreck in 2007 and is currently at risk due to its position off the Kent coast.

The Rooswijk wreck lies at approximately 25 metres of depth in a highly dynamic environment. It takes a lot of effort to excavate a shipwreck under these conditions.

‘Through mini excavations in the lab, we now know so much more about the ship, the people on board and their trade. I am happy the objects and the exciting stories they behold are now ready to be shown to the world.’ said Martijn Manders, Rooswijk project lead, Cultural Heritage Agency of the Netherlands.

Sixty eight etched sabre blades were part of the treasure.