Published online 18 May 2009 | Nature | doi:10.1038/news.2009.484

News: Q&A

Underwater archaeologist Jon Henderson is hoping to reveal the secrets of the ancient Greek town of Pavlopetri.

A building at Pavlopetri Jon Henderson

A few metres under the sea, near the town of Neapolis at the southern tip of Greece, lies Pavlopetri. Discovered and mapped in the 1960s, it will become the first underwater town to be digitally surveyed in three dimensions. Nature News caught up with Jon Henderson, an underwater archaeologist at the University of Nottingham, UK, before the project began on 18 May.

What does Pavlopetri look like? <br/> The site is submerged in about 3–4 metres of water, and covers an area of about 500 square metres, about 50-60 metres offshore.

There are about 15 buildings made up of three or four rooms, some streets, rock-cut tombs and courtyards — and there could be more underneath, because so far there has been no excavation. Some ruins date from at least 2800 BC, but we think the town Pavlopetri itself dates from the Mycenaean period, about 1600–1100 BC.

Because it's not on land, it hasn't been interfered with by agriculture, and it hasn't been rebuilt on. It's exactly as it was, although eroded down to floor level. We've still got the threshold stones from doorways and stones for grinding grain, for example.

Are there other submerged towns around the world like it? <br/> Pavlopetri is the oldest submerged town we know of, although no doubt others will be discovered. The city of Alexandria is the other one that's well-known — but most of the remains there are from the first millennium BC. In the eastern Mediterranean in particular, there are hundreds of submerged sites, because it is one of the earthquake centres of the world and there has been so much land movement.

It has been known about for a while, hasn't it? <br/> It was discovered in 1967 by Nicholas Flemming, who was then at the University of Southampton, UK, and who is one of the founding fathers of underwater archaeology in Britain. He's part of our team now — he's in his seventies, still madly excited about these sites and he still dives.

A team from the University of Cambridge, UK, mapped the site with tape measures in 1968, and recovered a few artefacts. We're going back now to increase the accuracy from the two-dimensional hand-taped plans. This month is just the survey stage, and the second stage will be three to four years of excavation.

Divers explore the site Jon Henderson

How are you mapping the town? <br/> We're using 'scanning sonar', which has been developed by an offshore engineering company [Kongsberg Mesotech in Vancouver, Canada, a subsidiary of Kongsberg Maritime, headquartered in Norway]. Their equipment does the same thing a terrestrial laser scanner would do, only using acoustic signals. It can take thousands of points over a couple of minutes and also take photorealistic impressions, so we could produce three-dimensional models using this equipment. Until now, sonar hasn't been able to produce as accurate a survey as terrestrial techniques. But if it does deliver everything it is supposed to, it could completely revolutionize underwater archaeology. Getting decent plans quickly is often a problem, and we often use measuring tapes and lines — which is effective, but time-consuming.

Was it ruined before it was submerged, or eroded underwater? <br/> We don't know. The fact that it wasn't rebuilt on, and that the pottery seems to stop at around 1180 BC, would suggest that it was submerged pretty soon after that date, but that's just a hope at this stage.

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What is particularly archaeologically interesting about the site? <br/> First, it's from the Mycenaean period. This is ancient Greece in the last phase of the Bronze Age, so the historical setting for much literature and myth. All the epics of Homer, for example, are reflected back to these periods. The Mycenaeans's power came from having control of the sea, but we know virtually nothing about the harbour towns. Pavlopetri is presumably a harbour town, where ships might have been brought in, unpacked and loaded and sent off again.

Also, the depleted oxygen levels in the water and the fact that any remains would be sealed in with sand makes for an anaerobic situation, and that could preserve organic artefacts, such as wooden tools. We'd be very lucky, but the possibility is there.