A 2,200-year-old Roman shipwreck surfaced with its hull sealed in pine tar and beeswax

A merchant ship that sank in the Adriatic more than two thousand years ago has yielded a rare, intimate look at the craft of keeping wooden vessels watertight. Researchers examining the wreck found its hull still coated with the substances Roman shipwrights used to fend off the sea, including pine tar and, in at least one spot, a mixture of tar and beeswax. Preserved for over two millennia, those brittle layers now serve as a chemical diary of how the ship was built, sailed, and patched up over its working life.

The wreck off the Croatian coast

The vessel, cataloged as Ilovik-Parzine 1, went down about 2,200 years ago near what is today the Croatian island of Ilovik, in waters that were then part of the busy trade network of the Adriatic. It dates to roughly the mid-second century BCE and was a working cargo ship, hauling timber logs and amphorae, the large ceramic jars that carried wine, oil, and other goods across the ancient Mediterranean.

First located by divers in 2016, the wreck survived in good enough condition that researchers could sample the material still clinging to its timbers. That preservation is what made the study possible, because the coatings that would normally rot or wash away had instead endured on the sunken hull.

Pitch as the workhorse of ancient waterproofing

Most of the protective layers turned out to be pitch, a sticky, water-resistant substance made by heating conifer resin until it thickens into a tar. Ancient shipbuilders relied on it heavily, smearing it over hulls to seal gaps between planks and block seawater from seeping into the wood. According to an analysis of the coating, pine tar dominated the samples taken from the wreck, confirming its role as the standard defense against leaks.

What makes the find valuable is not that pitch was used, which scholars already knew, but that it survived in a form detailed enough to study directly. Instead of inferring ancient practice from written descriptions alone, researchers could analyze the actual material that once sealed a specific ship, tracing exactly how it was formulated and applied.

The rare recipe of tar and beeswax

One sample stood out from the rest. It contained an unusual blend of pine tar and beeswax, a combination that matches a substance described in ancient texts, including the writings of the Roman naturalist Pliny the Elder. Adding wax to the tar changes how the coating behaves, making it more flexible when cold and thinner and easier to spread when warm.

Those properties would have been especially useful for repairs, as noted in a report on the study. A waxed tar that flows readily when heated and resists cracking in cold conditions is well suited to patching a hull quickly, whether at sea or during a hurried stop in port. Finding the mixture on a real wreck gives physical confirmation to a technique previously known mainly from ancient literature.

Pollen as a hidden geographic tracer

Beyond the chemistry of the coatings themselves, the researchers found something they could not have gotten from the words of ancient authors: pollen trapped inside the layers. Because tar is sticky when applied, it captured tiny grains of pollen from whatever plants grew nearby at the moment it was spread, effectively recording the surrounding landscape. Different regions carry different pollen signatures, so those grains functioned as a geographic fingerprint.

Reading that fingerprint, the team concluded that the ship was probably built near present-day Brindisi in southern Italy, then repaired more than once as it worked its way around the Adriatic. As the researchers described, the layered coatings preserved a travel history, marking not just where the vessel originated but where it was later maintained.

A hull that records a working life

Taken together, the coatings turn the wreck into a document of a single ship’s career rather than a static snapshot of the moment it sank. The presence of multiple layers and at least one specialized repair mixture suggests the vessel was patched and re-sealed over time, the kind of ongoing upkeep any long-serving cargo ship would have required. Each layer captures a distinct episode of building or repair, stacked one atop another on the surviving timbers.

That level of detail is unusual in ancient shipwreck studies, where the organic materials that reveal such histories rarely survive. By combining chemical analysis of the tar with the pollen locked inside it, researchers could reconstruct both how the ship was maintained and roughly where those repairs happened, information that would otherwise be lost.

What the coatings teach about ancient seafaring

The broader lesson is how sophisticated and adaptable ancient waterproofing could be. Roman-era sailors did not rely on a single crude sealant but adjusted their materials to circumstance, blending wax into tar when flexibility or easy application mattered. The wreck shows those choices preserved in physical form, aligning practical shipboard know-how with the descriptions left by writers like Pliny.

For archaeologists, the Ilovik-Parzine 1 offers a rare convergence of chemistry, botany, and ancient text, all pointing toward a fuller picture of Mediterranean seafaring. A ship that sank carrying timber and amphorae has, in the end, delivered its most valuable cargo in the form of the humble coatings that once kept it afloat.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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