An Ocean of Data: Looking for Sunken Treasure in a New Way

Search Team The Alkyon, which provides an operations base for underwater robot searches, sails past Fort Koules on the Heraklion harbor. Courtesy Dimitris Sakellariou/Hellenic Center For Marine Research

Early last October, Brendan Foley found himself on a small, inflatable boat making rings in the middle of the Aegean Sea. The 43-year-old maritime archaeologist was waiting on three divers, who were searching for ancient shipwrecks 100 feet below. Rather than drop anchor, the boat’s skipper, a potbellied Greek man named Giorgos, held the wheel hard to port, spinning the boat around and around. Whether inured to the repetitive course or just oblivious to it, Giorgos didn’t appear to mind making circles. But the repetition was making Foley antsy. He fidgeted with the zipper on his wetsuit. He rearranged the dive gear, still dripping wet from his own survey earlier that day. Then he sat down next to me and made an unusual confession for someone whose livelihood is tied to the sea. “I hate small boats,” he said. “Not too fond of big ones either.”

What Foley likes is finding shipwrecks, which is why he and his Greek colleagues chose the day’s dive site, Dia, a small, rocky island about eight miles north of Heraklion, the capital of Crete. The city has been an active port for about 6,000 years. In that time, it is likely that many Heraklion-bound ships wrecked on the cliffs of Dia. Jacques Cousteau found several wrecks on the island’s south shore in 1976 while searching for Atlantis. Foley and his team were the first archaeologists to search the north shore.

As much as Foley likes discovering shipwrecks—he’s found or helped find 26 in the past 14 years—he doesn’t much like spending time looking for them, at least not in the conventional ways. Rather than sending dive teams down to survey 1,000-foot transects one fin kick at a time, Foley prefers to use autonomous underwater vehicles (AUVs) to survey huge tracts of seafloor. Where the robots don’t work well, Foley sends down divers armed with closed-circuit rebreathers and thrusters, allowing them to cover more ground. He wants to go faster, he says, because he needs a lot more information. Maritime archaeologists can spend years on just a few sites, but for Foley’s purposes, a solitary wreck is statistically weak—nothing more than a few words from a greater conversation. To understand the entire conversation, maritime archaeologists must study many wrecks and identify patterns between them. Foley’s model is not the soft science of digging and interpretation, but the hard science of high-throughput screening deployed by gene and drug researchers, who gather data at an industrial rate and analyze that data with powerful computers able to detect subtle patterns beyond the reach of ordinary analysis.

Foley: Archaeologist Brendan Foley uses rebreathers to extend dive times to as long as three hours.  Courtesy Giogos Koutsouflakis/Ephorate of Underwater Antiquities

If Foley can determine where hundreds or even thousands of ancient ships were headed, when they were headed there, and what they were carrying, he could use computer analysis to trace the origin of the world’s earliest cultures, and in so doing he could test his central hypothesis: that it was seaborne trade that enabled the spread of civilization in the Mediterranean Basin. But to do all of that on a computer, he first wants to “map, in exquisite detail, the entire seafloor of the Mediterranean,” a sea that covers nearly a million square miles and may contain as many as 300,000 wrecks.

Today is proving to be especially difficult. Foley’s AUVs wouldn’t work near Dia; its steep undersea cliffs interfere with the robots’ sensors. Someone also left a critical part of the thrusters back at the dock in Heraklion. Instead of finding wrecks fast, Foley’s team was left to search out wrecks the old-fashioned way. He and his dive partner had made one dive earlier and had come up with nothing.

After a few more minutes spent motoring in circles, Foley took action. Earlier in the morning, Giorgos mentioned how much he’d enjoy diving in the area, so Foley, in his typical collegial manner, suggested that it was a good time for him to do just that, and added: “Mind if I drive?” Taking the helm, Foley backed the engine down to an idle. The boat slowed, bobbing over mild swells bearing south toward Dia’s yellow cliffs. The temperature was about 80 degrees and the visibility underwater about 100 feet. Now at least in control of something, Foley looked comfortable, happy even.

Given a choice, though, Foley would not be on a small boat on a perfect day. He wouldn’t even be on a large boat. Instead he would be seated on his tiled patio in Heraklion poring over the latest data collected by his robots.