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Shipwrecks are time capsules. A crew’s equipment, a passenger’s belongings,
and the remains of cargoes from ancient merchant ships can give us a fleeting
glimpse of ancient life and trade. Over the past 30 years, underwater archaeologists
have uncovered fascinating details of Greek, Roman and even more ancient
civilisations.

Mediterranean underwater archaeology really began with the invention
of the aqualung in 1943. But in those early days, many land archaeologists
were sceptical about its ability to meet their exacting standards. Then,
in 1960, George Bass and a team from the University of Pennsylvania proved
them wrong by meticulously excavating a Bronze Age wreck at Cape Gelidonya,
off southwest Turkey. Now a staggering 100 or so pre-Medieval wrecks are
discovered every year, with the total already running to well over a thousand.

Sports divers discover most of them. But the sheer number of sites means
that only about a third are visited – often only briefly – by archaeologists,
and just a fraction of these wrecks are excavated. Another problem is that
of the ‘clandestini’, or wreck robbers, who plunder and destroy many sites
before they can be recorded.

The Mediterranean is the last great repository for works of art, especially
bronzes. Even accessible, shallow waters continue to produce spectular finds.
In 1971, a spear-fisherman discovered two 5th century life-size bronze statues
at Riace, off southern Italy; and magnificant life-size bronze Poseidon
– now in the Athens Archaeological Museum – was dredged from the sea near
Boeotia in central Greece.

Wrecks also provide remarkable evidence for ancient technology. Back
in 1990, helmeted sponge divers salvaged the ‘Antikthera computer’ from
a 1st century BC wreck off the southern Greek islands after which it is
named. The device is 14 centimetres across, with 30 interconnected bronze-toothed
cogs, and it is astonishingly sophisticated. Crafted with the precision
of a clock, it was probably used as a navigational calculator.

The range of materials that can be preserved underwater is enormous.
Organic remains, such as timbers, will survive if buried in a relatively
anoxic environment where there are no boring worms (Teredo navalis) or marine
gribble (Limnoria lignorum). Outside the Mediterranean, the Mary Rose, sunk
in the Spithead channel off Portsmouth in 1545, is a familiar example. Ancient
hulls can be preserved extraordinarily well: archaeologists know of about
200 wrecks with some timber remains.

Objects found on board are just as revealing. Delicate organic remains
found recently include a small folding wooden writing board, from a 14th
century BC wreck at Ulu Burun, Turkey; wooden calipers from a 6th century
BC Etruscan wreck off Tuscany; and, from the same region, many dozens of
sealed glass phials, their contents still intact, from a doctor’s medicine
chest discovered inside a Roman wreck of the 1st century BC. Amphoras, the
large, two-handled pottery jars of antiquity, are often found stoppered
with food remains. Such preservation does not depend on a wreck being intact.
Divers found that a late Roman wreck only 4 metres deep off Randello, southern
Sicily, held unbroken amphoras filled with fishbones, buried in sand.

But perhaps the most interesting artefacts are the cargoes carried by
the ancient merchant ships. Almost all wrecks are of merchant ships. Divers
have found only one ancient warship, a 3rd century BC Punic vessel grounded
off western Sicily. Most warships would have perished as flotsam, but the
weight and durability of cargo often mean that wrecked merchant ships survived:
in some cases, the cargo pinned down and preserved the lower hull.

Merchant ships transported an immense variety and quantity of goods.
The most common cargo is pottery amphoras, which are easily spotted by divers.
Other goods were often carried alongside. A spectacular 11th century Arabic
cargo at Serce Limani, off Turkey, contained glass as raw cutlets and as
blown vessels, and Italian archaeologists excavating a 3rd century Roman
wreck near Trieste, in northern Italy, have found glass vases. Stone cargoes
included columns, blocks millstones and sarcophagi.

Wrecks also reveal trade in raw materials and consumables, such as unworked
ivory tusk from Ulu Burun, kernals of grain from a 6th century wreck off
southern France, and even pig bones, the remnants of a consignment of pork,
from a 3rd-century wreck at Giglio Porto in Tuscany. Ships also transported
several types of raw metal, from the 2nd millenium BC bronze and copper
ingots of Ulu Burun and Cape Gelidonya to Roman cargoes of led and iron.

More than two thirds of all wrecks discovered so far date from between
the 4th century BC and the 5th century AD. In the first half of this period
the Romans rapidly expanded their control over much of Italy and Sicily,
Gaul, Spain, and North Africa, and eventually the East. From the 1st to
the 4th century, the Mediterranean was in many respects a unified market,
free form piracy and warfare, and long-distance trade in exotic goods, from
Eastern spices to African circus animals, was commonplace. In addition,
Sicily, Spain, Egypt, and North Africa provided staple foodstuffs for Rome’s
million-strong population, for other large cities and for the frontier armies,
while the emperer’s political security depended partly on handouts of grain,
olive oil and other staples.

Most wrecks are found in the western Mediterranean, off Provence in
France, Tuscany in Italy, Bonifacio in Corsica, the Balearics, the Aeolian
Islands, ahd southeast Sicily. This reflects both the routes of amphora
transport and the regions where divers have been most active. Elsewhere,
exploration has been sporadic, as in the Adriatic, or virtually non-existent,
as off North Africa. Only a few wrecks have been found along the entire
coast between Morocco and Egypt. The same is true of the Black Sea, although
more finds are now being reported from Bulgaria. In the Aegean, the best
discoveries have been off southwest Turkey, where local sponge divers have
led teams from the Institute of Nautical Archaeology at Texas A&M University
to several dozen well-preserved wrecks. American and British teams have
carried out similar investigations off Cyprus. Further east, the only important
concentration of sites is off Israel.

The location of these wrecks also tells us a lot about patterns of ancient
shipping. Mediterranean seafaring for colonisation and trade must have been
widespread well before 3000 BC; the distribution of obsidian and pottery
reveals a flourishing Aegean network. We have some idea of these early boats
from pottery and wall paintings. Most were probably oared and lightly built,
not much bigger than a modern dory, so they would be unlikely to leave a
visible wreck. We know of only one wreck that is probably older than 2000
BC: it lies in shallow water off the Greek island of Dhokos. As yet, no
one has excavated it thoroughly, but we know that it contained many hundreds
of small pottery vessels, from about 2500 BC, and a stone anchor. A similar
anchor of between 1900 to 1200 BC, found on land in Lebanon, weighed between
500 and 700 kilograms, so some ships at least must have been quite large.

After about 1500 BC – the late Bronze Age – wrecks begin to give a detailed
pictures of the civilisations they represent. Excavation of the Cape Gelidonya
wreck in 1960 revealed a ship about 10 metres long, dated by radiocarbon
and by stylistic analysis of pottery to the 13th century BC. Its main cargo
was 34 four-handled copper ingots of a distinctive ‘oxide’ shape, each weighing
about 25 kilograms. There was also residue from ingots of tin, which would
have been mixed with copper to make bronze. Interspersed among these ingots
were baskets of bronze tools, most broken before the wrecking and apparently
carried as scrap. The ingots were probably cast in Cyprus, and the ship
may have belonged to an itinerant Syro-palestinian metal merchant.

In 1983 Bass and his team were rewarded with a second Bronze Age wreck,
the marvellously opulent site at nearby Ulu Burun. This wreck was about
a century older than the one they had excavated two decades previously,
at Gelidonya. here too, the ship was travelling from the east, and seems
to have been of a Canaanite rather than a Mycenaean Greek merchant. Substantial
sections of hull timber are preserved, and teams from Texas A&M University
have excavated a dazzling cargo: Mycenaean, Cypriot and Near Eastern pottery;
copper and tin ingots; bronze tools, including axes, adzes, drillbits, and
tongs; cylinder seals, with hierogrlyphic markings; a dagger, a dirk, and
arrowheads; a stone plaque; objects in amber, shell, bone, and faience (a
molten silicate similar to glass); and a magnificant gold chalice and gold
jewellery. They prove that seaborne transport prospered more than a thousand
years before Greaco-Roman trade reached its peaks.

The Gelidonya and Ulu Burun wrecks mark the beginning of a Mediterranean
nautical tradition. Balance-pan weights from a merchant ship at Ulu Burun
resemble those found on Byzantine ships almost 2000 years later, suggesting
a common type of commercial activity. The Ulu Burun ship carried a cargo
of Canaanite jars, forerunners of the ubiquitous amphora. The modest size
of the two ships seems typical of later amphora merchant ships, which appear
in pictures as propelled by a single, continuously adjustable square sail
and double steering oars. From their kitchen and table utensils, it seems
that crews were often small, sometimes only for or five men.

About 1100 BC the Mycenaean world collapsed, and Greece plunged into
a dark age for which no wrecks are recorded. Then in the 8th to 6th centuries
BC, expanding city states such as Corinth began colonising the rich lands
of the western Mediterranean. Early on, these ‘archaic’ Greeks established
contact with the remarkable Etruscan civilisation of central Tyrrhenian
Italy. The Etruscans controlled the rich iron mines of Elba and the Tuscan
coast; in return for iron, the Greeks supplied many goods, including fine
painted pottery.

The wreck that best confirms this Etruscan link is at Giglio Campese,
in the Tuscan archipelago. When Mensun Bound and his team from Oxford University
excavated this much-looted site between 1982 and 1986, they found an early
6th century BC collection of Etruscan amphoras, some of which probably had
contained pitch, and ingots of copper and lead. There were also wine and
olive oil amphoras from the Greek island of Samos and Asia Minor, and painted
fine wares, including 20 or more ‘aryballoi,’ round-bodied vessels about
the size of ink pots, used for carrying unguents and perfumes. Many of these
came from Corinth, reflecting the city’s commercial and political prominence.
Small copper nuggets may have been pre-coinage currency.

Other objects found at the site match those of Ulu Burun in diversity
and wealth: a magnificent bronze helmet, and arrowheads; a writing plaque;
an ellborately carved wooden lid; gaming pieces; and fragments of ornate
inlaid furniture. Delicate wooden pan pipes recall the Etruscan love of
wind music noted by Roman writers.

From the 4th century BC, the number of wrecks increases sharply, reflecting
Hellenistic trade from the Aegean and a boom in amphora production in the
Roman west. Parts of Sicily and western Italy began making wines for export,
packaged in local ‘Graeco-Italic’ amphoras that mimic Greek ones; the scale
of this transport is seen by the number of wrecks off the Aeolian Islands.
By the 1st century BC, flourishing Italian vineyards were exporting vast
quantities of wine. Wreck evidence then tracks a reversal in this trade,
as wine producers in southern Gaul and Tarraconensis – modern Catalonia
– began to establish a place in the Italian market.

In the 1st century BC, the focus shifts again to the ancient southern
Spanish provinces of Baetica and Lusitania. Their export of olive oil, fish
and wine dominated the western amphora trade for the next 200 years. The
scale of Baetican oil export was immense: in Rome, a 50-metre high wharfside
mound of discarded amphoras contains an estimated 40 million containers
of this period – the equivalent of 6 million tonnes of oil. And there are
dozens of Spanish wrecks along routes crossing the Balearic Islands and
the Strait of Bonifacio.

But by the early 3rd century this traffic was being ousted by export
from Proconsularis and Tripolitania in Africa, now modern Tunisia and western
Libya. There are at least 100 wrecks with African cylindrical amphoras,
which were still being exported 200 years later.

Underwater archaeology continues to fill in the details of this picture.
Some of the most interesting wrecks are the massive wine carriers of the
late Roman Republic of the 1st and 2nd centuries BC. A well-preserved example
at Madrague de Giens, near Toulon in southeastern France, is about 35 metres
long and could carry about 400 tonnes, or at least 6,000 amphoras. Andre
Tchernia of the University of Aix-en-Provence heads the excavation, which
is still incomplete after 13 seasons. Some ships of this trade were even
larger: one salvaged in the 1950s near Albenga in Italy had mas many as
10,000 amphoras. Amphora ships of this size are exceptional: usually they
are 16 to 20 metres long, with about a 70-tonne capacity, and smaller ships
of 12 to 16 metres carrying about 200 amphoras are also quite common.

The large size of these late Roman merchant ships reflects the wealth
of the estate owners and their willingness to invest heavily in ships plying
the safe, short route between central Tyrrhenian Italy and southern Gaul.
The wine merchant could also be the ship owner: at another wreck off southern
France, divers found the name of the merchant Sextus Arrius stamped on both
cargo amphoras and lead anchor stocks. Shippers also traded in other goods.
At Madrague de Giens, gaps between the amphoras, stacked four high, were
filled with hundreds of attractive ‘Campanian’ (southern Italian) black-glased
bowls and plates. This packaging explains how everyday items were dispersed
so widely around the Roman Mediterranean.

If we move on several centuries, and further south, wreck archaeology
off southeast Sicily gives us a detailed picture of amphora trade from the
late 2nd to the 5th century. The area between Gela and the Strait of Messina
was a busy crossroads where many African and Eastern ships floundered on
the dangerous reefs, or were taken unawares by the unpredictable winds.
Since the late 1950s, many archaeologists have studdied the area, from Gerhard
Kapitan, a local amateur, to teams from British universities, led by Anthony
Parker from Bristol University, and more recently, under my direction from
the University of Cambridge.

Some of these wrecks are particularly interesting. Around AD 200, a
small merchant ship, probably sailing from Tunisia to Rome, sank off Plemmirio
in southeast Sicily. The 200 or so cylindrical amphoras on board marked
the beginning of large-scale export of amphoras from Africa. Some were lined
with resin, and probably contained fish produce; other, unlined ones may
have carried olive oil. Iron bars stacked among them were probably for sale
as the ship passed through ports or were carried under contract to another
merchant.

One end of the ship, including the galley, sank intact. Its contents
give a vivid picture of life on board. The galley house was roofed with
pottery tiles; inside was a brick-and-stone hearth, surrounded by pottery
dishes, jugs, bowls, a glass bottle, four pottery oil lamps, small amphoras
for storing water and a stone mortar for grinding grain. Lead fishing weights
suggest how the crew supplemented their diet. But perhaps most interesting
was the discovery, unique on an ancient wreck, of three bronze scalpels;
they probably belonged to a passenger, who may have been an eye surgeon.

Several kilometres west, in only 5 metres of water, is a scattered wreck
of about the same age containing distinctive high-handled Aegean amphoras.
This resurgence of the Aegean wine trade coincided with the massive transport
of stone columns and blocks, quarried in the same area. These were meant
for building projects in Rome and other western cities. The 2nd and 3rd
century stone wrecks off Sicily – at Taormina, Marzamemi and Isola della
Correnti – are impressive: one column alone at Marzamemi weighs an estimated
40 tonnes. Another wreck off Marzamemi contained the prefabricated stone
facing of a 7th century church; it was probably intended for one of the
flourishing Byzantine communities of southern Sicily or North Africa.

Two scattered, shallow wrecks off Sicily show the changing nature of
the amphora trade by the 4th century. At Femmina Morta, a wreck of about
AD 300, most amphoras are African, but there is a greater variety of types
and some Spanish containers. North African ports acted as transhipment centres
where all sorts of goods could be laden into one cargo: the wreck at Femmina
Morta also contains red-glazed fineware and the small pottery ‘vaulting
tubes’ once used to reinforce concrete masonry.

The second wreck, at Randello, also held amphoras from southern Spain.
They were full of sardine bones, evidently of fish transported whole, perhaps
for processing into garum, a favoured sauce made from the effluvia of decomposed
fish entrails. There are many sardine shoals around Gibraltar, and the ruins
of Roman fish-salting installations survive on both sides of the Strait.
The fish were graded and sorted quite carefully before packaging.

From subtle variations in the shape of the Randello amphoras, we think
that the fish-salters were supplied by small workshops employing two or
three master-potters. Their cylindrical form copies the efficient shape
of Tunisian amphoras, and reflects increasing standardisation of form irrespective
of origin. By the 5th and 6th centuries, empty amphoras may have been transported
as a commodity, or reused; by the 7th century, both these activities were
common.

Now some underwater archaeologists are looking to the well-preserved,
undisturbed sites that lie beyond the safe air-driving limit of 50 metres.
People have discovered such wrecks during seabed pipeline surveys and submersible
testing. Last year, Robert Ballard and his team from the Woods Hole Oceanographic
Institute – they found both the Titanic and the Bismarck – pinpointed a
4th century amphora wreck at 800 metres in the central Tyrrhenian Sea.

But exciting though these finds are, the expense and logistics of deep
search are often prohibitive. A more realistic focus may be inshore sites
in depths of 50 to about 150 metres, which can be reached by divers with
special equipment. One possibility is saturation air-diving, where a chamber
is used to keep divers continuously under pressure; the equipment and expertise
is still costly, however. In the future, diving archaeologists may be able
to use oxygen mixtures, such as Heliox, which substitute a less toxic gas
for nitrogen and allow free diving to depths beyond 50 metres.

Meanwhile, archaeologists have important work to do at sites at easily
accessible depths. Many known wrecks, some found decades ago, are incompletely
characterised or unpublished, while many more await discovery. As they piece
together the evidence, underwater archaeologists will reveal not only spectacular
objects, but more fascinating insights into the day-to-day life of the world’s
great ancient civilisations.

1: Techniques of underwater technology

Exacavation, whether on land or under the sea, should be of comparable
quality. Underwater archaeologists may therefore spend as much time surveying
the site, collecting information about its surrounds, and recording artefacts,
as their land colleagues. Archaeologists use both grid and open area excavation
techniques. In the former, they cover the site with a metal or plastic grid
of metre squares, which are excavated one by one; in the latter method,
they strip down larger areas layer by layer. The locations of finds are
mapped by measuring distances from two or more datum points whose positions
are fixed on the site plan.

Range sightings are made as on land: a measuring pole is sighted through
a device which calculates distance from the angle of vision. Wrecks, which
result from one brief event, do not have the layers of finds through time
often seen on land, but they can be excavated and recorded in a similar
way. Seabed sediment may stabilise into distinctive layers according to
coarseness of grain, often covering a grey-black, anoxic layer beneath.
Sometimes, at a well-preserved, upright wreck, divers can excavate through
layers of cargo, ballast, timber and other materials still in their shipboard
configuration.

‘Eyeball survey’ remains the best way of discovering ancient wrecks
in the Mediterranean, where a scatter of pottery often can only be seen
from close up. Nowadays, archaeologists can find more recent and larger
wrecks, especially if they contain a lot of iron, by proton magnetometer
survey and echo-sounding (sonar). They have also used remote sensing outside
the Mediterranean, notable in Britain, to search for wrecks buried in the
Goodwin Sands off the Thames Estuary.

But underwater archaeologists have had to develop special tools and
adapt old techniques. For example, to help them measure differences in depth,
they use a standard diver’s oil-filled depth gauge. A length of clear garden
hose, strung from a datum point, adds precision; because of water pressure,
an air bubble introduced at one end will rise to a constant level, from
which the relative depths of various points around a site are plumbed.

Another advantage is in removing sediment. The underwater equivalent
of trowelling is to waft away sediment by gentle hand movements, either
downcurrent or into a suction tube that disperses material some distance
away. The most familiar suction device is an airlift – an upright tube through
which air pumped from a surface compressor rises to form a vacuum. Small
dredges, where water is pumped backwards through a tube to provide suction,
are used at sites too shallow for an effective airlift.

Many difficulties are easy to deal with. A perspex board with replacable
sheets of coarse drafting film and a graphite pencil replaces a clipboard,
the land archaeologist’s basic tool. Simple ideas are often best: at the
Yassi Ada Byzantine wreck, off Turkey, George Bass’s team discovered that
the most effective way to hold exposed wood fragments in place was to pinion
them with bicycle spokes.

Artefact conservation is a special bugbear of underwater archaeology,
just as in the excavation of inundated ‘wetlands’ sites. Organic materials
that are well preserved underwater may be extremely fragile on exposure
to air. Researchers pack finds in sand-filled trays and raise them from
a site using ‘lifting-bags’ – ventable air balloons controlled by a diver.
Then they transfer their finds to a conservation laboratory, where they
add stabilising solutions to the water in which they are constantly soaked.

Hull timbers are most often raised individually. Waterlogged wood poses
special problems, as it is usually the largest organic find and withers
away if left to dry. The most successful treatment – used first on the early
17th century warship Vasa, raised intact in 1962 from Stockholm Harbour
– is to saturate the timber with polyethylene glycol (PEG), which eventually
replaces the cellular structure of the wood. But it is time-consuming and
costly, so hull timbers are often reburied once they have been recorded
and sampled.

Divers have with special physiological problems. Even at a shallow Mediterranean
site, a fully wet-suited diver may be debilitated by cold after an hour
or two; below about 30 metres the water is as cold as off Britain. For divers
using compressed air, either from tanks (SCUBA – Self Contained Underwater
Breathing Apparatus) or supplied by a ‘hookah’, from a surface compressor,
underwater time is limited by the danger of a nitrogen ‘bend’. As pressure
increases with depth – by about one atmosphere every 10 metres – the bloodstream
absorbs larger quantities of nitrogen, which expands when the diver ascends
and must be allowed to dissipate. A bend, often crippling or fatal, happens
when a diver decompresses too quickly to prevent the formation of a bubble
of nitrogen, which may then lodge in the brain or a joint. The only treatment
is immediate recompression in a chamber. A diver can only stay at a depth
of 30 metres for 20 minutes without having to undergo long decompression
stops on ascent, and below 50 metres the risks are too great. The toxicity
of pressurised mitrogen also has an anaesthetic effect, expecially apparent
below 40 metres, which may leave a diver incapable of performing quite simple
tasks. Deep excavation, in 40 to 50 metres, is only justified if the site
is exceptional and if there is a professionally managed recompression chamber
with the expedition.

Deep projects are also expensive, so archaeologists focus increasingly
on shallow-water surveys and sample excavations. A typical British university
expedition in the Mediterranean lasts for about two months and involves
about twelve people, operating from inflatable boats and running thier own
air compressor.

2: Clues from the pottery of the past

Amphoras are among the most familiar of ancient artefacts – cheaply
produced, disposable pottery receptacles manufactured in vast quantities
for the transport of everything from wine, olive oil and fish sauce, to
nuts, meat, lime and pitch. They were exported to the outposts of the Roman
Empire, to Britain and India, but are associated particularly with sea-borne
trade in the Mediterranean. Their pointed bases meant that they could be
stacked in interlocking layers, and also made carrying and pouring easier.

The pots held typically 20 to 60 litres – easily handled by one or two
men. They are seen as early as the 2nd millennium BC, in the Mycenaean and
Canaanite East. Byzantine and Arab merchants of the later 1st millenium
AD still used them, although by then less pottery was being made, and reusable
wooden barrels were becoming more popular. The olive jars of 17th and 18th
century Spain reflect a persistent tradition, however, and the two-handled
shape survives today in north African Egyptian water jars.

Amphoras can be dated and their place or origin identified. They may
provide the basis for archaeological statistics of trade, so their study
has become a flourishing topic in Roman archaeology. It was a 19th century
German scholar, Heinrich Dressel, who founded the study of amphoras. He
nearly went blind in his fastidious recording of their epigraphic markings
– impressed stamps and painted inscriptions that indicate the place of origin,
name of the producer, or contents.

Particular shapes can often be tied to region, date of manufacture,
and sometimes specific contents; thus for example, the long-handled Dressel
1 is an Italian wine amphora of the 2nd to 1st century BC, the globular
Dressel 20 a south Spanish oil amphora of the 1st to 3rd century AD, and
the cylindrical Dressel 27 a later form typical of north Africa.

On land, Roman amphoras are often found in rubbish deposits of discarded
pottery near what was a wharf or market. Important shipwreck finds have
also contributed to research since the 1950s. Characterisation techniques
have become more sophisticated, and thin-section petrology, the microscopic
study of ceramic, is now standard. The particular mixture of clay in an
amphora may be typical of a form and of a manufacturing region. Neutron
activation analysis, used to study trace elements in clay, can pin down
shards to a particular area or kiln complex, but it depends on many local
samples being available for comparison.

Another important area of study, still being developed, is that of amphora
contents, using gas and high-pressure liquid chromatography to identify
olive oil lipids inpregnated in amphora shards, for example.

David Gibbins is a maritime archaeologist based at the University of
Cambridge.