New Research

This Medieval Byzantine Shipwreck Boasts More Gold Treasures Than Any Other Vessel Found Beneath the Mediterranean

The vessel sank in the Adriatic Sea in the seventh or eighth century C.E. Its cargo included a gold signet ring likely associated with the emperor Heraclius and gold belts encrusted with rubies, emeralds and pearls

Meilan Solly | Senior Associate Digital Editor, History

July 28, 2026 4:07 p.m.

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The waters off the coast of Mljet, a Croatian island in the Adriatic Sea, are home to more than two dozen sunken ships spanning nearly 2,500 years. But one stands out as “the most important shipwreck of its period,” opening a portal into a little-known chapter in Byzantine history, Justin Leidwanger, an archaeologist at Stanford University, tells Reuters’ Antonio Bronic.

The vessel in question sank in the seventh or eighth century C.E. with a rich cargo of gold belt sets adorned with precious gemstones, as well as coins minted under four emperors from the Heraclian dynasty.

Excavations also unearthed a gold signet ring that may bear the likeness of the dynasty’s founder, Heraclius, who ruled the Byzantine Empire between 610 and 641. Per a statement from the state-run Croatian Conservation Institute, which started surveying the wreck in 2015, the ring could only have been worn by a high-ranking official authorized to seal documents in the emperor’s name.

Collectively, the gold treasures recovered from the vessel weigh more than 21 ounces, making the trove the largest of its kind “ever found on a shipwreck in the entire Mediterranean,” Igor Miholjek, the institute’s head of research, says to Reuters.

The ship sank during the period once known as the Dark Ages, named after the widespread cultural decline that supposedly took place across Europe at the time. More recent research has debunked the myth of intellectual stagnation between roughly 500 and 1000, but written records from this period are scarce, and many aspects of the early medieval era remain poorly understood.

“It’s a blank,” Francesco Borri, a medieval historian at the Ca’ Foscari University of Venice who wasn’t involved in the research, tells National Geographic’s Roff Smith. “That’s why the discovery of this ship is so exciting.”

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How does the Mljet shipwreck fit into this story? As Smith writes for National Geographic, the vessel sank “when the fortunes of the Byzantine Empire were at a low point and when some historians believe that the Adriatic was an impoverished backwater, virtually devoid of shipping.” The ship’s cargo suggests otherwise, testifying to continued maritime activity in the region.

Still, scholars say that the curious assortment of goods recovered from the wreck raises more questions than answers. Why, for instance, was the ship carrying so much goldsmithing equipment? Perhaps the gold belt sets, some of which were already decades old when the vessel set sail, were slated to be melted down and reforged in a newer fashion. Alternatively, could these luxury items have been intended as gifts for a foreign power? If so, why was the wreck also carrying mundane cargo, including amphorae, ceramic pottery and game board pieces?

To find answers to these questions, the researchers plan to continue analyzing artifacts associated with the wreck, in addition to revisiting the site in search of further evidence.

For now, the exact nature of the doomed voyage remains unclear. But Miholjek tells National Geographic that “whatever was going on here, this was no normal trading venture.” The presence of gold treasures directly linked to a Byzantine emperor suggests that a high-ranking official was traveling on the ship, perhaps at the head of a diplomatic party bringing gifts to a faraway ally. Alternatively, it’s possible that the individual was simply a wealthy elite who booked passage on an otherwise ordinary cargo ship.

“The material evidence does not yet force a choice between those explanations,” medieval history enthusiast Luciano Anastasi writes on his blog. “What it does rule out, or at least weaken sharply, is the image of a routine small-scale coaster carrying nothing but staple goods between neighboring ports.”

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Meilan Solly is a senior associate digital editor at Smithsonian magazine, where she oversees the online history section. Solly's specialties are Tudor England, medieval Europe and World War II.