So I’m watching through a Teaching Company course on classical archaeology that I borrowed from my pastor. From start to finish it has been a fascinating course. Indeed, I found it so fascinating that I ordered the new course on the archaeology of the Holy Land.
At any rate, in one lesson the professor was talking about how they wanted to figure out if sailors in the classical period, hugged the shoreline of the Mediterranean, as everyone assumed, or if they navigated out of sight of land. They were able to answer that question by following the emptys.
What they did was get some submersible cameras fitted on diving platforms. They knew that over the years, much traffic had gone between Rome and Carthage. So they set out from the island of Sardinia, with these cameras and monitored them 24 hours a day. Sardinia is roughly halfway between Rome and Carthage.
After a time period in which they found nothing, they suddenly began to see amphoras on the ocean floor. They soon discovered more and more and found that the empty amphoras tracked a straight course between Rome and Carthage, proving that ancient sailors were fully capable of sailing out of sight of land. The theory (which seems correct to me) being that, if you were sailing a cargo of amphoras of wine between Rome and Carthage, you were probably going to get into the cargo on the way, and toss the empty overboard. Over the centuries and centuries of classical period, a veritable treasure trove of empty amphoras traced a straight line from Rome to Carthage.
And that is how they discovered that ancient sailors were not afraid of leaving the sight of land, and could navigate over open water.