Underwater Archaeology

Terra firma poses enough problems for archaeologists, but excavating under the sea poses some serious challenges. Underwater archaeologists have to contend with tumultuous tides, poor visibility, and rapidly-changing conditions. But it's worth it.  In their hunt for lost worlds and legends, underwater archaeologists have their goggles firmly focused on the ancient world, and have made some startling breakthroughs.

From Diving Bells to Aqualungs

Despite the sophisticated technological set-up that you might assume to be crucial to the job,  underwater archaeology has existed almost as long as the discovered treasures themselves. Alexander the Great is said to have explored the seas using a diving bell fully to the depths of 25m. This construction was made of colourless glass to help the user see more clearly, and was lowered with ropes suspended from a boat. The man-sized diving bell continued in use throughout ancient and medieval times, until 1535 when Guglielmo de Lorena was reputed to have used the first true diving bell, involving a barrel-shaped headpiece.

De Lorena's apparatus, which could only sustain as much air as could be carried in the large helmet, was pretty much the pinnacle for underwater breathing technology until the aqualung was invented in 1943 by Emile Gagnan and Jacques Cousteau. This ground-breaking paradigm allowed underwater archaeology to gather pace, and in 1960 the American archaeologist George Bass carried out the marine excavation of a Bronze Age ship at Cape Gelydonia in Turkey. His work shattered theories that effective archaeological research could not be carried out beneath the sea, and the discipline has been in full swing ever since.

Today underwater archaeology is just as respected, if not more so, than its land-based brother, and recent hauls have not only been eye-catchingly great to look at, but have changed the way we view the ancient world's relationship with maritime travel, trade and warfare. Today the technology with which experts scour the seabed for ancient clues has moved on a great deal from the days of Cousteau and co., but the basic techniques remain the same, and not all that different from land-based excavation. Scholars still put their bodies on the line in wet suits and breathing apparatus, but increasingly robotic and single-manned submersible vehicles are being used as safer and more precision tools for unlocking the ancient treasures of the ocean.

Tools of the Trade

Of course, before an excavation project can begin in earnest, one first needs to locate the desired wreckage or remains. For this, experts may themselves dive to the bottom of the sea to check first-hand what the situation is. Sometimes sonar is used from a boat on the surface, or a magnetoscope checks for deviances in the earth's magnetic field. This will flag up any ferrous material below, more useful for the excavation of modern seafaring craft, but also for ancient vessels laden with metalwork and metal artefacts.

Once something of interest has been sighted, preparatory techniques are much the same as land-based digs, as reference grids are placed on the seabed using nylon tape, and excess undergrowth and other material is painstakingly cleared using a hand-held lancet. Uncovering objects underwater is a particularly delicate operation, as more often than not the desired item has achieved a sort of equilibrium with its surroundings, and has effectively become part of the landscape over the centuries, or millennia, in which it has been entombed in its watery shrine.

There are several specific techniques which can be used to minimise damage. Particularly deep digs may employ unmanned submarines to clear a path through treacherous waters where artefacts  have been lost in the deeper recesses of the earth's oceans.

Most archaeological research carried out underwater thus far has been concentrated on the areas around the Mediterranean Sea, and the ships lost to their great civilisations.

For these, divers may use a variety of hand-powered tools, such as vacuums, which are designed to allow their users easy access to artefacts whilst disturbing their surroundings as little as possible.

In this sense, again, underwater work is largely the same as its land-based equivalent, yet the equipment needed to carry out such operations invariably makes underwater work a lot more expensive and time-consuming. The Dover Bronze Age Boat, for example, the oldest discovered seafaring vessel in the world, took its excavators no less than seven years to pinpoint, research and lift from its watery grave.

Careful Drying

As has been mentioned previously, underwater artefacts, especially those of the ancient world, are usually bound to their environment like a snail to its shell, and need the utmost of care to ensure they don't crumble to pieces when taken from the sea. If dried with simple evaporation, wood and leather, which form the vast majority of underwater ancient finds, will corrode irreparably. Thus scientists have developed two major techniques to avoid artefact destruction, both of which are usually used in conjunction to produce the sort of effects seen in many ancient hauls.

VIDEO: Underwater Archaeology at Aswan - Dr Hawass at the Nile

Firstly, to minimise any chance of degradation during the drying process, the material is impregnated with polyethelene glycols (wax), which increases in volume as water decreases. When this process is completed, which can take a huge amount of time (the English Tudor warship Mary Rose, lifted in 1982, underwent its impregnation phase from 1994 to 2004), the object can begin to be dried.

Drying ain't that easy, either. Instead of leaving the artefact to dry naturally via evaporation, it must first be frozen, then its ice-based moisture sublimated instantly into a vapour which condenses on chilled metal rods. Sounds difficult? It is, and many important items were lost until we reached the painstaking stages we have today (to revisit the Mary Rose, drying will not even begin until 2010, with an estimated time of completion as yet beyond its custodians). Again, all this adds up, so its thankful that some of the world's most startling discoveries have been made under the surfaces of the sea.

Major Finds

Of course, that semi-mythological jewel in the crown of underwater archaeology, Atlantis, still seems a world away from the technology and methods of today's experts – not for a lack of trying, it must be said – but there have been plenty of amazing discoveries made much closer to home. The aforementioned Dover Bronze Age Boat is one of the most stunning. Whilst working on roads in the Kentish town of Dover in 1992, authorities noticed an odd piece of wood jutting out of a waterlogged hole which had already thrown up pieces of the town's medieval and Roman past. It was soon surmised that they had actually discovered the first prehistoric boat on British shores since 1937, when a Bronze Age boat was discovered in Yorkshire. That boat had disintegrated due to the lack of conservation know-how at the time; no such mistake would be made this time. After excavating for months, the boat was impregnated with wax for over a year before being freeze-dried. Its 1575 – 1520 BC oak and yew-lashed hull stands as one of the crowning glories of underwater archaeology, usurping by date the mass of discoveries off the coast of Turkey, which made George Bass a name for himself in the 1960s. Many similar finds have been made from Roman, Greek and Carthaginian provenance.

Settlements have also been uncovered by the grace of underwater archaeology. Alpine Neolithic settlements have been located at the bottom of bodies of water like Lake Geneva, confirming the succession of the three archaeological states (Stone, Bronze and Iron) in the region.

One of the more exotic discoveries was made in 1992, when India's National Institute of Ocean Technology uncovered the remains of a potentially pre-Harappan city, which they believe dates as far back as 7,500 BC, in the Gulf of Cambay off the country's west coast. This would totally shatter preconceptions about the origins of civilization if true, and proponents say it would have been submerged during the last ice age, around 9-10,000 years ago. Subsequent results on the city's dating have been sketchy thanks to the perils of the area's seas, with treacherous waves and prodigious rip tides making surveillance almost impossible. If proven, however, the city would throw the debate about the cradle of civilization – at the moment thought to have originated in Sumer – right open.

One city which has been the subject of a hugely successful underwater project has been is the Egyptian coastal stronghold of Alexandria, and in particular its lighthouse, which is one of the seven ancient wonders of the world. A 1994 search found blocks from what is believed to be the famous outpost, alongside other treasures like obelisks, sphinxes and columns. Though firm conclusions have been hard to come by, the project's French proponents are convinced they've found the wonder. Other monuments found by the team include statues to the Ptolemaic kings of Egypt which have transformed the way that archaeologists have viewed Greek rule in Egypt.

In conclusion it would be fair to say that, while underwater archaeology has plenty in common with its land-based cousin, it does pose a number of dangers, both to the intrepid explorers undertaking it but also in terms of cost and conservation. But there will always be a fantastic romance connected to the treasures of the deep, and thanks to myths and legends like Atlantis, and exciting modern excavations such as those in the Saronic Gulf of Greece, sea-based exploration shows no sign of abating.

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About The Author

Sean Williams

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Sean is an English Literature graduate, who currently works as a writer and journalist in London. He enjoys ancient history, theatre and sport. He does not enjoy Big Brother.