Underwater excavations near the diving destination of Kaş on south-west Türkiye’s Mediterranean coast have brought to light a 1,100-year-old shipwreck – and a sealed amphora that has yet to reveal exactly what it contains.
Amphoras surviving for more than a millennium with their contents intact are extremely rare, and this one is said to represent a first for Türkiye. The vessel has now been recovered and opened, but the results of analysing its clay-like contents are still awaited.
A 20-strong archaeological dive team from Akdeniz University led by associate professor Dr Hakan Öniz has been excavating the wreck on behalf of Antalya Museum, as part of a Ministry of Culture & Tourism initiative called “Legacy for the Future Project”.
The merchant ship appears to have sailed from Gaza in Palestine before running into a storm off Kaş. From the amphora design it is thought to have been carrying a cargo consisting mainly of olive oil. In March it was announced that olive seeds had been found inside one amphora at the wreck-site.
The wreck lies near Besmi island at depths of around 45-50m, and the team has made use of an ROV as well as scuba to maximise bottom time.
Complicated process
The amphora was taken to the university’s Underwater Archaeology Laboratory, where it took an hour to open and sample the contents. However, the analysis is said to be a complicated process because of the length of time the jar has spent under water.
According to Prof Öniz it could have been used to transport olive oil, olives, wine, the fish sauce garum or something else entirely. “The opening was thrilling, but waiting for the result is even more exciting,” he said.
Olive oil was Gaza’s primary export at the time, and Palestinians were not thought to have been wine-drinkers in the 9th and 10th centuries, but the ship had in any case probably stopped at several ports between there and Kaş. If wine was carried, it most likely originated in Turkiye.
Artefacts recovered from the Kaş wreck are likely to be displayed at a projected Mediterranean Underwater Archaeology Museum in Kemer.
Also on Divernet: 10,000 ceramics found on ancient Med shipwreck, Divers find dagger on world’s oldest merchant shipwreck, Black Sea wreck’s identity hidden by ghost-nets
That’s an interesting finding. But as SCUBA divers we should have a better idea than most how odd a finding this is. The amphora’s sinking (and attached ship) has taken a brittle, rigid vessel (amphorae are made of fired clay) filled with a fluid and (probably) a gas bubble. (Ever tried to fill a bottle completely, with no gas bubble? With a nice easy screw cap. Now try doing it with some rig up of wax-soaked wooden plug, and more wax to close the top of the plug. Tricky!)
Now you take the sealed rigid brittle vessel, containing a liquid and a gas bubble, And you increase the external pressure from one atmosphere (plus or minus about 10% with the weather) within (however long a ship takes to sink – minutes, or 10s of minutes?) to 5 or 5.5 bars external pressure. But even if the sealing material is somewhat pliable, and the gas bubble is small, the internal pressure in the amphora might only increase by a fraction of an atmosphere. We did these calculations in our “gas law” parts of diver training. This is what happens (in reverse) with the gas bubble in our blood, if we haven’t done our decompression calculations properly. We know that is potentially bad news.
Then, after sitting on the bottom of the sea for 1100 years (rather off our decompression tables), they hauled it back to the surface. Since the seal probably leaked enough to equilibrate pressure with the seabed in the first century or so, that probably means the pressure in the ascending amphora considerably exceeded the external pressure as the lift bag (or ROV) ascended. For things like fired pottery products, this is not good. When I was coring rock samples in oil wells we had strict rules about slowly raiding the rock samples through the last 4 or 5 km of the seawater column. And every body got very very annoyed about the delay of a day’s “decompression time” for the rock samples. I’ve friends in the commercial diving sector, for whom a week of decompression (in the “pot”, not in the water; but nonetheless, a week) is standard. Bringing this stored pressure, potentially explosive vessel to surface must have been a long drawn-out process.
So far, we’ve assumed there is no change in the contents. That is … optimistic, to the extreme. It has been sitting at about 4 or 5 bars pressure with some seawater in contact with whatever the original contents were. Is there going to be a reaction? In 11 centuries? Who knows. Will any reaction produce gases? Or convert some of the liquids to denser solids, and decrease the pressure in the vessel. We had a whole family of procedures for examining that for oil well samples too – we called it “headspace analysis” – because we’d analyse gases in the “head space” above a filled pressurised sample. But we’d be accessing that through a valve we’d designed into the equipment before we sent it “down”. This amphora’s designers probably didn’t include that. Which makes piercing the seal … somewhere between challenging and scary.
I’m even more surprised they got it to surface, intact.
There’s a lot more behind this story than there first appears. And as trained divers, we should have a better understanding of that than the man in the street. It might even form the basis for some challenging exam questions for trainees. If you’re feeling sadistic.