Sault Ste. Marie, Michigan sits along the St. Marys River in the Upper Peninsula, straddling the U.S.–Canada border opposite its larger Canadian twin city of the same name. The two cities are connected by the Sault Ste. Marie International Bridge, and between them lie the famous Soo Locks — a set of five ship locks that act, as Gates puts it on camera, like a "water elevator" bridging the 21-foot elevation difference between Lake Superior and Lake Huron. Up to 10,000 vessels pass through the locks annually, making this one of the busiest commercial waterways in North America. Settled by mostly French colonists in 1668, the city is recognized as the oldest in Michigan. Gates used the Soo Locks as his entry point into Lake Superior while investigating the fate of three French minesweepers — the Inkerman, the Cerisoles, and a third vessel — that disappeared on the lake in November 1918, beginning what he describes as a search for "the deadliest wrecks in Lake Superior's history."
Sault Ste. Marie settled by mostly French colonists, becoming what is now recognized as the oldest city in Michigan
Three French minesweepers depart Thunder Bay bound for the Atlantic via the Great Lakes waterway; two — the Inkerman and the Cerisoles — disappear on Lake Superior
Gates travels through the Soo Locks at the start of his Expedition Unknown investigation into the lost WWI minesweepers (S12E05)
The Soo Locks are one of the most consequential pieces of civil engineering in North American history. Without them, the vast iron ore, grain, and coal resources of the Upper Great Lakes region would be essentially landlocked, unable to reach the manufacturing centers and ports of the lower Great Lakes and beyond. The current lock system has been expanded and modernized over more than a century, though the fundamental engineering principle — using gravity-fed water chambers to raise and lower ships — dates back to the mid-nineteenth century.
The historical backdrop Gates investigates is well-documented: three French minesweepers, the Inkerman, the Cerisoles, and a third ship, were built in the Canadian port city of Thunder Bay (then Fort William) near the end of World War I and were intended to be delivered via the inland Great Lakes waterway to the Atlantic. Only one vessel completed the journey. The Inkerman and Cerisoles vanished on Lake Superior in November 1918, a notoriously brutal month on a lake known for its violent late-season storms. Their loss has been a subject of ongoing interest among Great Lakes maritime historians, though the wrecks' precise locations remained unconfirmed at the time of Gates' investigation.
Sault Ste. Marie itself carries deep historical weight beyond the locks. As a city settled in 1668 — making it Michigan's oldest — it was a critical node in the French fur trade network and later in the development of the American Upper Midwest. Its position on the St. Marys River, the only natural outlet of Lake Superior, meant that whoever controlled this narrow passage controlled access to an enormous interior waterway system.
Gates' episode uses Sault Ste. Marie and the Soo Locks primarily as a dramatic threshold — the gateway through which the doomed minesweepers passed and through which Gates himself travels to begin his search. The episode does not present definitive conclusions about the wrecks at this location; rather, it frames the locks as the starting point of a broader Lake Superior investigation, with Gates heading up the coast after his transit to pursue further leads.
Sault Ste. Marie, settled in 1668, is the oldest city in Michigan.
The Soo Locks use only gravity — no pumps — to move more than two million gallons of water to raise or lower ships the 21-foot elevation difference between Lake Superior and Lake Huron.
Up to 10,000 vessels pass through the Soo Locks annually, making it one of the busiest commercial waterway systems in North America.
The St. Marys River, along which the city sits, forms part of the United States–Canada border, with the Canadian city of Sault Ste. Marie, Ontario directly across the water.
The Soo Locks are generally accessible to visitors year-round, with a dedicated park and observation platform on the American side operated by the U.S. Army Corps of Engineers where you can watch massive freighters transit the locks up close — no ticket required. The adjoining Soo Locks Boat Tours offer guided passages through the locks themselves during the navigation season, which typically runs from spring through late fall. Check current local schedules and advisories, as lock operations are subject to seasonal and maintenance closures.
Sault Ste. Marie, Michigan is itself the nearest city; the larger regional hub of Marquette, Michigan is approximately 340 miles to the west.
Late spring through early fall offers the best combination of active shipping traffic, mild weather, and open tour boat operations. Summer months tend to draw the largest crowds to the observation deck.
Lake Superior
Lake Superior is the body of water Gates enters after transiting the Soo Locks and is the primary search area for the lost WWI minesweepers Inkerman and Cerisoles investigated in S12E05.
Lake Michigan
Lake Michigan is another of the Great Lakes sharing the same interconnected waterway system that the French minesweepers were navigating when they disappeared.
Normandy Beaches, France
The lost minesweepers were French WWI vessels, connecting the investigation thematically to broader World War I maritime history explored in other Gates expeditions involving European battlegrounds and wrecks.
Historical data sourced from Wikipedia