In a “once-in-a-lifetime discovery,” underwater archaeologists have uncovered 22 ancient shipwrecks near the small Greek archipelago of Fourni.

The wrecks span the ages—from around 700 BCE to the 16th century CE. For nearly 2000 years, the dozen-plus islands of Fourni saw a lot of traffic while serving as a stop within a massive network of long-distance trade routes between the Black Sea, Aegean Sea, Cyprus, Egypt, and the Levant. Most of the wrecks—all of which are the remains of merchant ships—date to the Late Roman period, from the 4th to the 7th century CE.

Peter Campbell, co-director of the Fourni Underwater Survey, told Discovery News: "Surpassing all expectations, over only 13 days we added 12 percent to the total of known ancient shipwrecks in Greek territorial waters."

This was the first time an underwater archaeological survey had been conducted in the area. But since the archipelago was more of a rest stop than a destination, the volume of wrecks surprised even the experts. In fact, the sheer number of wrecks was so surprising to the Greek-American team that at one point, overwhelmed by the findings, they stopped looking for new wrecks in order to focus on cataloging the already discovered ones. Scholars believe that even more have yet to be found—perhaps as many as 40 in all.

The many wrecks were likely caused by storms or equipment malfunctions, though the area was also known for piracy.

While much has been lost to time and the elements, the amphorae discovered among the wrecks offer much to be studied and conserved. Pottery that once held things like fish sauce and olive oil now contain valuable insights for scientists about how people in the ancient world traded and navigated on the open sea.

[h/t Independent]