Archaeologists have discovered a shipwreck off the coast of Croatia containing an extraordinary wealth of gold jewelry, coins, pottery and a signet ring that may have belonged to one of the most important functionaries in the Byzantine Empire. It dates to the late 7th or early 8th century, a period from which few written records have survived, making this discovery all the more important.When the ship sank off of Mljet island in the Adriatic Sea, it was carrying commercial cargo and a likely high-ranking Byzantine official as a passenger. Mljet was located on an active shipping route between Western and Eastern Europe, linking northern Italian cities including Ravenna and Venice to Constantinople and other Byzantine cities of the Near East. Despite the maritime activity, only one other Byzantine wreck has been found, and it dates to the 11th century so this one is much older.The remains of the ship were first surveyed in 2014 by a team of underwater archaeologist with the Croatian Conservation Institute. The shapes of the amphorae made it clear that this was a Byzantine ship from the 8th century. Located at a depth of 460 feet on a steep seabed, conditions were so challenging dives could only be done over a few weeks during the summer. A decade of slow, targeted excavations ensued. Every stage sectioning, documentation, excavation took longer than it would have in an easier spot to ensure that best archaeological practices were followed. The most recent maritime exploration discovered a unique treasure of mens gold jewelry and fittings.The most remarkable finds include four gold belt sets, gold buckles and decorative belt ends adorned with emeralds, rubies and pearls. These luxurious objects once decorated the leather belts of senior Byzantine dignitaries. According to the Institute, comparable items have never previously been discovered at an underwater archaeological site in the Mediterranean.Researchers also recovered gold coins depicting four emperors from the Heraclian dynasty, dating from the end of the 7th century. The coins are particularly important because they may help archaeologists establish more precisely when the ship sank.One of the most intriguing discoveries is a gold ring bearing the image of an emperor from the Heraclian dynasty. Such a ring could only have belonged to someone at the highest level of the Byzantine state or military administrationan individual authorised to seal imperial documents.The ship also carried standard commercial goods, like amphorae used to transport oil and wine, ceramic dishware like bowls, jugs and plates, ivory game tokens and dice. Archaeologists believe the ship may have been on a diplomatic mission, to deliver tribute to an ally. One of the gold belts is very similar to one found in an Avar tomb on the mainland, suggesting the objects were manufactured in the same workshop and then sold.