Underwater Conservation and Preservation at Ses Llumetes

The underwater site of Ses Llumetes, in Porto Cristo (Mallorca), is one of the most significant in-situ conservation projects in the western Mediterranean. Since 2014, conservators’ interventions have focused on the in-situ preservation of the Roman ship structure dating to the mid-1st century AD, in accordance with the principles of the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage.

Underwater photo of a diver holding on to one of the wooden planks of the wreck. — Figure 1: Preservation tasks conducted during the 2022 archaeological campaing.

Interventions have included innovative techniques for the consolidation, stabilization, and in situ protection of the hull structures, using polyester resins, reusable sandbags, structural stitching with PVC cannulas (Figure 2-3), and protective coverings of textile mesh and sand layers, creating an anaerobic environment that slows natural decay. These solutions have proven to be reversible, cost-effective, and efficient against environmental and anthropogenic factors, allowing the preservation of archaeological timbers and associated materials in exceptional condition.

Underwater photo of a diver just above the wreck with what looks like a pin cushion full of small, curled plastic tubes attached to their wrist. — Figure 2: Deatil image of the PVC cannulas employed in the stiching and preservation of hull structures.

Underwater photo of a diver wrapping a small plastic tube around a wooden plank of the wreck. — Figure 3: Consolidation of hull remains using PVC cannulas.

The Ses Llumetes project pushes forwartd viable and innovative restoration technologies towards creating a sustainable and economical conservation model, increasingly focused in recent years on reducing environmental impact by integrating sustainability criteria into every intervention. Thanks to international collaboration between the IBEAM and the University of Victoria (Canada), it has been possible to develop pioneering strategies that serve as a reference in other Mediterranean contexts, as evidenced by publications in the proceedings of the International Symposium of Conservation for Underwater Archaeology (ISCUA)

Front and back views of an oval-shaped, flat wooden object with a fragment of rope coming out of the middle and rope-sized holes positioned on either side of the central hole through which the rope is coming out. — Figure 4: Front and back of the wooden deadeye, with remnants of rigging lines preserved inside. Found in Sector A4.

These objects were carefully documented, stabilized, and treated under strict conservation conditions. In the laboratory, the wooden objects underwent cleaning, desalination, and progressive consolidation with polyethylene glycol (PEG) (Figures 5-6), culminating in freeze-drying at the Centre for Underwater Archaeology of Catalonia (CASC), a technique that removes water without structural collapse and enables long-term preservation.

Thanks to these efforts, two of the treated pieces are part of the travelling exhibition entitled “Naufragis” by the la Caixa Foundation, which brings the value of the Mediterranean’s underwater cultural heritage to a broad audience, highlighting the importance of seafaring and its archaeological remains for understanding the evolution of humanity, as well as the advances in underwater archaeology showcased through several projects.

Three wooden objects submerged in water inside a large, clear container. — Figure 5: Application of PEG 4000 to the objects recovered from Ses Llumetes.

A woman in a lab setting wearing latex gloves is holding a dropper over top of a small circular metal plate on a small machine that also has a digital screen. — Figure 6. Measurement of PEG concentration (%) using a refractometer.

This project has only been possible through international public and private funding, with a prominent role played by our research project, generosluy founded by the The Social Sciences and Humanities Research Council (SSHRC), whose support has supported and enabled the development of pioneering in situ conservation measures. Nevertheless, it is essential to strengthen this commitment and increase investment in order to expand research in the cove of Porto Cristo and to continue restoring the recovered materials, thereby ensuring that this archaeological and cultural legacy is passed on to future generations.

Image of the wreck taken around the water line. Both the wreck under water the shore line above water in the distance are visible in the image. — Figure 7. Image of the Ses Llumetes wreck under the waters of the Porto Cristo cove.