Recent advances in deep-water technology have opened vast swaths of the ocean previously unavailable to humans. Up until the mid-20th century, underwater exploration was limited to a depth of about 200 feet, representing about 5% of the ocean. We now routinely go 20,000 feet and beyond. We’ve even visited the deepest point—the Challenger Deep, in the Mariana Trench, some 36,000 feet below the surface—multiple times now. For the first time, we have access to ocean in its entirety.
A diver at the site of the shipwreck off the coast of Tonga Photo: AFP/Matafonua Lodge/Darren Rice
And in these abysmal depths lay untold billions in sunken gold, silver, and emeralds, not to mention priceless caches of cultural history thought to be lost forever. How much is all this hidden treasure worth? UNESCO estimates there are three million shipwrecks underwater right now. No one has any idea exactly what each was carrying, so any guess as to value is speculation. And a gold coin fetched from a shipwreck and brought to market without context is worth the value of gold—no more, no less. But a gold coin retrieved and documented with archeological diligence and sold as a historical artifact is worth much, much more.
Our new technological capabilities stem not from revolution—sonar has been around for over a hundred years; submersible vessels since the mid-18th century—but of refining, allowing for deeper dives on sounder information. Take, for instance, the El Faro, a US cargo ship sank by a hurricane off the Florida Keys last October, taking all 33 sailors aboard with it. After weeks of intense search and rescue, the vessel was located at some 15,000 feet, or about three miles, below the surface—a depth utterly impossible to reach or explore a few decades ago.
The damaged stern of the sunken freighter was photographed under 15,000 feet of water off the Bahamas. Photo: National Transportation Safety Board
Much of the technology used to recover El Faro—side-scan sonar, magnetometers, remotely-operated vehicles—is shared by the military, oil and telecommunications industry, and, controversially, deep-sea treasure hunters. Over the last two decades there has been a proliferation of “commercial salvagers”: private companies, funded by investors or countries, who hunt for shipwrecks in this newly accessible abyss, selling off what they find.
Treasure hunting is an enormously risky enterprise. The first step to discovery is hardcore historical and scientific research. Software capable of crunching huge amounts of data on things like local water currents and wind speeds, and improved databases that collate old shipping records and manifests, give salvagers at least some idea where to dive and what they hope to find. Though less sexy than an Exosuit, this step is far more crucial; even if we could reach the ocean’s floor, it’s unlikely we’d find anything in the sprawling, relentlessly dark sea without solid intel.
The promising region is then scoured with magnetometers: high-powered, ultra-sensitive metal detectors that are towed behind the ship, looking for steel and iron. Sonar devices have also become one of the most important instruments for treasure hunters. Weighing about 3,500 pounds and shaped like a missile, side-scan sonar devices are towed behind a ship, creating detailed, 2-D topographical maps of the seabed at depths of 20,000 feet. They generally come with two frequencies: the lower frequency can search farther and wider, but in less detail; the higher is focused, capable of rendering smaller areas with crisp fidelity. Unnatural geometry like straight lines or perfect circles merit a closer look.
Blending oxygen with other inert gases like hydrogen—a mix known as hydrox, one of many such cocktails—allows divers to go hundreds of meters deeper than hitherto possible, and with less decompression sickness and few “deco” stops. But there are depths we still can’t dive. For this we need ROVs (remotely-operated vehicles): robots connected by fiber-optic cables to the mothership, outfitted with high-def video cameras, lights, sensors and mechanical arms that let sailors on the surface poke around and collect samples. Their hydraulic arms are strong enough to hoist hundreds of pounds. Thrusters allow them to move in all directions, and even hover like a helicopter. Some models have a detachable side-scan sonar device, making them a fully integrated, dual-body search-and-rescue machine.
Since the ‘80s, ROVs have become standard, as they grow increasingly cheaper and more sophisticated. Recently, Autonomous Underwater Vehicles (AUV) tech has matured to the point where battery-powered, unmanned vessels can travel pre-programmed paths without an umbilical, collecting massive amounts of data on their own. It’s feasible, perhaps inevitable, that in the near future, thousands of AUVs will be at work mapping every foot of the ocean floor with sonar and magnetometers. A day may come when every single shipwreck has been discovered, and all treasure harvested.
The legality of treasure hunting is a mess. Each country—and in the US, each state—makes it own laws regarding private salvaging of artifacts, and often these laws are disputed by other countries or international bodies. One critical issue is the care with which salvagers exhume artifacts. Since their incentive is money, “worthless” things like broken pottery are ignored, robbing archaeologists—or all of us, really—of precious insight into the past. Some question the ethics of disturbing what could be considered a grave at all.
The precedents are contradictory. Back in 1985, the famed deep-sea explorer Mel Fisher discovered the Atocha, a Spanish vessel sunk in the Florida Keys in 1622. After spending millions of dollars and 16 years of effort, Fisher found the ship, which held a treasure worth about one billion in current USD. Florida and the Feds claimed ownership, trying to force him to sign a contract forfeiting a quarter of his findings. The case went to the Supreme Court. Fisher won it all; finder’s keepers was the verdict.
But in 2007, Odyssey Marine Exploration, a Tampa-based company, made a similar discovery: $600 million in treasure from a Spanish warship sunk off the coast of Portugal in 1804. Spain sued for ownership. This case also went to the Supreme Court, but Odyssey lost. They even had to pay $1 million in legal fees.
In 2012, just a few years later, that same company made a deal with the British Maritime Heritage Foundation to find and retrieve a warship lost in 1744. After the site was fully documented by archaeologists, the nonprofit would reimburse Odyssey for their costs, and pay 80% of the market value for items used for commerce, like coins, and 50% for objects of war, like weapons. It’s estimated the gold alone, if sold for historical value, is worth $1 billion.
This deal offers a reasonable model for the successful, ethical treasure hunting. After all, if private companies weren’t remunerated at all for their effort, they’d either quit declaring their findings or stop searching altogether. In either case, humanity loses. An arrangement that balances all interests, filling our museums with priceless historical artifacts and compensating those that do the work, is, one hopes, the future of treasure hunting.
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