A casual swim near Sardinia has turned into one of the most significant archaeological finds in recent memory. Just off the coast of Arzachena, a diver spotted bronze glinting from the seabed and alerted authorities. What they uncovered was a treasure trove of fourth-century Roman coins—somewhere between 30,000 and 50,000 pieces scattered in the shallow waters.
These coins lay in a sandy zone bordered by underwater seagrass, forming a natural time capsule from the late Roman world.
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Importance
“This is one of the most important coin discoveries in recent years,” said Luigi La Rocca, who oversees archaeology for Italy’s Ministry of Culture. His statement makes it clear this isn’t just a collector’s dream—it’s a major historical find.
Why should people who aren’t into ancient coins care? Because discoveries like this shine a spotlight on how the Roman economy functioned, how trade routes formed, and how ordinary people—farmers, merchants, and soldiers—moved through that system.
Location
The find was made off Sardinia’s northeastern coast, near Arzachena. The seabed here is shallow, allowing ocean currents to move items across a broad zone while still preserving them in sand and seagrass.
Two main clusters of coins were identified within these sandy pockets, with seagrass forming natural boundaries. These underwater plants help hold sediment in place, stabilizing coins and amphora fragments while leaving just enough exposed for discovery.
Clues
Alongside the coins, investigators found pieces of amphorae—ceramic jars used to transport goods like wine, olive oil, and grain. Some jars appear to have come from North Africa, while others likely originated in parts of Asia. This mix suggests that trade vessels traveled long distances and carried products from multiple regions on the same journey.
Follis
Most of the coins appear to be folles—a type of large bronze currency introduced during Emperor Diocletian’s economic reforms. Originally weighing about ten grams, these coins had a thin silver wash to make them appear more valuable than their metal content suggested.
Over time, the weight and silvering declined, reflecting the empire’s financial strain. Still, folles remained a backbone of everyday transactions across the Roman world. A sailor in Sardinia might pay his tab with the same coin a landowner used in Gaul.
How They Got There
So how do thousands of coins end up underwater? There are a few possibilities. A storm might have sunk a ship. Or maybe the captain hid a large payment offshore, intending to retrieve it later.
The layout of the coins suggests they were once inside a container that broke open—scattering them across the sea floor. Some might have lodged in sand pockets, while others rolled further into seagrass beds. The gentle currents and topography here likely helped preserve the hoard.
Archaeologists will investigate whether there’s a nearby wreck and whether the amphorae and coins came from the same event. If they did, researchers could start to piece together what kind of voyage this was—and how it ended so suddenly.
Seagrass
One reason the coins survived so well is because of seagrass. In the Mediterranean, Posidonia oceanica plays a surprising role in underwater archaeology.
These underwater plants slow wave action, trap sediment, and create low-oxygen environments. That combination slows decay and can lock artifacts in place for centuries.
But seagrass meadows are shrinking fast—damaged by pollution, boat anchors, and warming waters. When they vanish, buried sites become vulnerable to erosion. So protecting these living mats is also a way of preserving human history.
Scale
To get a sense of just how big this discovery is, consider the Seaton Down Hoard found in the UK in 2013. That cache held just under 23,000 Roman coins and was hailed as one of Britain’s largest ever. Even using the lower estimate of 30,000, the Sardinia find easily surpasses that.
That puts it among the largest late Roman hoards ever discovered in the western Mediterranean.
Details
Roman coins are small, but they pack a lot of information. Each carries an image of a ruler, an inscription, and a mint mark. Once researchers log thousands of these details, they can build a timeline of emperors, trace economic shifts, and map how money moved across the empire.
If many coins come from a specific emperor or mint, that might suggest a political campaign or trade route. The corrosion layers can even reveal the chemical makeup of the local environment where the coin sat for centuries.
| Detail | Information It Offers |
|---|---|
| Emperor’s image | Identifies reign and time of issue |
| Mint mark | Shows where the coin was made |
| Metal composition | Indicates economy and inflation levels |
| Corrosion chemistry | Reveals water and sediment conditions |
| Tool marks | Suggests minting practices and technology |
What’s Next
Now comes the slow part. Conservators will carefully clean each coin using gentle methods to preserve their inscriptions. Once stabilized, the coins will be logged, photographed, and catalogued.
Experts in numismatics will analyze the designs, assign dates, and determine which emperors are featured. Meanwhile, archaeologists will catalog the amphora pieces and trace them to known pottery centers based on shape and clay type.
If the coins and amphorae came from the same voyage, they might help piece together what kind of cargo was aboard and why it ended up on the seafloor near Sardinia.
FAQs
Where were the Roman coins found?
Near Arzachena off Sardinia’s northeastern coast.
How many coins were discovered?
Between 30,000 and 50,000 bronze coins.
What type of coins are they?
Mostly folles, introduced during Diocletian’s reforms.
Why is seagrass important here?
It helped preserve the coins in low-oxygen sediment.
What comes next for the coins?
Cleaning, cataloguing, and study by numismatics experts.
