Mystery of Roman coins discovered on shipwreck island has archaeologists baffled

two worn roman coins in copper and silver
The coin on the left is a silver denarius minted in the reign of Antonius Pius, from A.D. 138 to 161. The emperor's head and some Latin characters can just be seen.The coin on the right is a silver denarius minted in the reign of Trajan, from A.D. 98 to 117. It shows the emperor's head and part of a Latin inscription. (Image credit: Johan Rönnby)

Archaeologists are baffled but excited by the discovery of two silver coins from the Roman Empire on a remote island in the Baltic Sea, halfway between Sweden and Estonia. 

No clues reveal how the coins got there, but they may have been left by Norse traders, lost in a shipwreck or brought there on a Roman ship that voyaged to the far north.

Johan Rönnby, an archaeologist at Södertörn University in Stockholm, was part of the team that found the coins with metal detectors in March, at a beach site marked by old fireplaces on the island of Gotska Sandön.

"We were so happy," he told Live Science. "We have this site, but we don't know what it is. But now that we have the coins there, it makes it even more interesting to continue to excavate it."

Roman coins

The two silver coins found on the island are both Roman "denarii"one from the reign of the emperor Trajan, between A.D. 98 and 117, and the other from the reign of the emperor Antoninus Pius, between A.D. 138 and 161.

They each weigh less than an eighth of an ounce (4 grams) and would have represented about a day's pay for a laborer when they were minted. 

Denarii were the standard coin of ancient Rome, and their name survives today in the word for "money" in several Latin-based languages, such as "denaro" in Italian and "dinero" in Spanish.

Rönnby said coins from the Roman Empire could have stayed in circulation for a long time, because the silver they contained always remained valuable; and they might have been brought to Gotska Sandön by Norse traders who had taken shelter there from storms at sea.

But it's also possible they were carried there by survivors from a shipwreck: The waters around the island are notoriously dangerous, and the area is littered with wrecks, he said.

Another possibility is that the coins were taken to Gotska Sandön by Romans on a Roman ship, though no records of such a voyage into the Baltic exist.

"It's not likely to be a Roman ship," Rönnby said. "But you have to consider also that the Romans were sailing up to Scotland and so on, and that there were Roman authors at that time writing about the Baltic area."

Baltic island

rocky beach with trees in distance

Gotska Sandön, or "Sand Island," is one of the most remote islands in the Baltic Sea. The coins were found at a site on the plateau above the modern beach. (Image credit: Johan Rönnby)

Roman coins have also been found on the larger island of Gotland about 25 miles (40 kilometers) to the south, but that was perhaps to be expected because it was the location of several towns. Gotska Sandön, however, has no towns or villages.

Gotska Sandön — meaning "Sand Island" — is uninhabited today but was home to lighthouse keepers in the 19th century. Before that it was known as a place of shipwrecks and as a haunt for pirates, Rönnby said.

Archaeologist Daniel Langhammer, who oversees cultural heritage on Gotska Sandön for Gotland County, told Live Science that the new finds echoed claims by a 19th-century lighthouse keeper that he'd found a Roman coin on the island. 

But the mystery of how the coins arrived might never be solved, he said. "We just don't know how they got there."

The remote island was also once frequented by seal hunters — seal hunting is now forbidden, but the seals are still there — and by fishers during the summer months, he said.

Rönnby and his colleagues, including Sabine Sten, an osteologist at Uppsala University, will return to the site later this year. They hope eventually to reconstruct the history of the remote island.

Live Science Contributor

Tom Metcalfe is a freelance journalist and regular Live Science contributor who is based in London in the United Kingdom. Tom writes mainly about science, space, archaeology, the Earth and the oceans. He has also written for the BBC, NBC News, National Geographic, Scientific American, Air & Space, and many others.

  • lol
    might of been domitian's or trajan's payment to decebalus, brought there by the latter's slavic subcontractors. i pretty much doubt the romans would have vacay in germanic lands.

    if anything it was easier to become slave than being a german back then. as a slave you can accumulate wealth, free yourself, and climb the social ladder, even one day can become an emperor like maximinus thrax.

    the office of the imperator is closed to the germans. see for instance flavius gaudentius and his son aetius, stilicho, thet no matter what they did for the glory of the empire or pull from the brink of destruction, they cannot become emperor themselves.

    EDIT: speeling
  • Hussar
    There should be no mystery about Roman coins found on Baltic island .Romans had contact with Baltic via what was known as the Amber Road from Northern Italy across Europe to Baltic coast in area of what is now known as Gdansksince the area of coastline was a major source of Amber trade for Rome.I am surprised that the archaeologists involved in these excavations are not aware of this since it is well documented in a number of history books.The Romans also traded via Lesko in what is now in the South East of Poland across the Bieszczady mountains into what is now the Ukraine for furs .Roman trading Post was discovered during construction of a Stadium in early 1960s in town of Lesko with Roman pottery (amphoras) .This fur trading route would have crossed Czechia,Slovakia to Dukla Pass and via Lesko to then proceed possibly via what is now the Medyka area onwards in to the depths of what is now Ukraine. I am aware of this because a close relative of mine was the archaeologist in charge of the Lesko dig being based at the museum in Sanok which was the main town and museum nearby.I added this info to show that the Romans had regular trade with Eastern Europe and finding Roman Coins in this area is unusual and rare but has a rational explanation.