Three men are sitting on the aft deck of RV Storm, a 50-foot research vessel bobbing gently on Lake Huron on a clear, warm July morning. They’ve more or less disappeared under shrouds of black neoprene, masses of corrugated and smooth tubes, and constellations of metal tanks, clips, and fasteners. Dive safety officer Jason Nunn calls out a checklist that sounds arcane even to an experienced scuba diver: “Press the ADV to ensure proper operation.” “Confirm computers are set for CCR mode and that you’re on the appropriate mix.” “Set your PO2 to 0.5.”
The divers—Russ Green, Joe Hoyt, and Tane Casserley—are underwater archaeologists with the Office of National Marine Sanctuaries of the National Oceanic and Atmospheric Administration (NOAA). They are wearing rebreather systems that scrub the carbon dioxide from their breath and recycle the air, allowing them to dive deeper and stay down longer than divers with traditional open-circuit scuba gear. In a few minutes, they will drop 165 feet through the clear, cold water to the wreck of Pewabic, a 200-foot-long freighter that sank in 1865 after a mysterious collision.
Pewabic is one of hundreds of wrecks and suspected wrecks in the Thunder Bay National Marine Sanctuary off the northeast coast of Michigan. Together, these historic ships embody the entire history of modern transportation in the Great Lakes—the story of the opening of the American continent to settlement and industry.