Photo: The tangled remains of a large steel crane at the shallow site of Haltiner Barge (aka Scanlon’s Barge), one of the stops on Alpena Shipwreck Tours. Photo: Thunderbay.noaa.gov

Alpena, Michigan, gateway to the Thunder Bay National Marine Sanctuary, offers a fascinating window into the maritime history of the Great Lakes.

With 160 identified shipwrecks and countless more waiting to be discovered, this underwater museum is a treasure trove for historians, divers, and curious visitors alike. But beyond its well-known status as a shipwreck haven, Thunder Bay holds many lesser-known stories and facts that deepen its allure.

“Before this was federally recognized as a preserve,” says First Mate James, who guides the Alpena Shipwreck Tours, “Sport divers petitioned the State of Michigan to protect our shipwrecks.”

Michigan designated the area an underwater preserve in 1980, covering 290 square miles. The sanctuary’s protection was further bolstered in the early 2000s when the federal government expanded it to cover a massive 4,300 square miles, stretching all the way to the international line with Canada.

Thunder Bay’s shipwrecks are preserved in a way that sets this sanctuary apart. “Believe it or not, Lake Huron has over 1,000 shipwrecks,” James shares. Within the sanctuary alone, 160 shipwrecks have been identified, cataloged, and marked, offering a unique glimpse into the region’s maritime past. The cold, freshwater environment of Lake Huron plays a crucial role in this preservation, slowing the decay that saltwater would hasten. As a result, the sanctuary’s shipwrecks are remarkably well-preserved, some even retaining their original structures for over a century.

For those who explore the sanctuary, whether through diving, snorkeling, or glass-bottom boat tours, the experience is akin to stepping back in time. “Our water is relatively clear. We’re not saltwater, so our shipwrecks, having been down here a long time, are well preserved,” explains James. While largely beneficial, this clarity is also aided by the unintentional help of an invasive species—the zebra mussel. “These things blanket the bottom of our lake bed; they attach to everything,” James notes. Though zebra mussels are often a nuisance, in this case, they act as a filtration system, helping to maintain the pristine underwater conditions that allow for such clear viewing of the wrecks.

Thunder Bay’s maritime history is not just about the shipwrecks themselves but also about the circumstances that led to these disasters. “There are a couple of reasons why we have so many shipwrecks,” James explains. Weather, fog, and topography are the main culprits. “Sixty-five percent of all shipwrecks in the sanctuary are caused by weather—pocket weather moving in at a moment’s notice,” he continues. The unpredictability of the weather in Thunder Bay, coupled with the lack of advanced navigational technology in the past, meant that many vessels met their fate in these waters.

Adding to the challenges was the topography of the lakebed, which is dotted with limestone deposits, sandbars, and boulders. “We have limestone deposits all over the place,” says James. Back in the day, sailors used rudimentary methods like sounding the seabed with a long line and a cement block to gauge depth and obstacles, but these methods were far from foolproof. The problem was that many times the ship was already on top of a formation when they found out about it. This complex underwater landscape contributed to the numerous shipwrecks, making Thunder Bay a particularly treacherous area for maritime navigation.

Beyond the shipwrecks, Thunder Bay National Marine Sanctuary also protects submerged maritime landscapes, including ancient shorelines and drowned riverbeds. These features provide valuable insights into the geological history of the Great Lakes and the early human habitation of the region thousands of years ago. The sanctuary’s role in preserving these landscapes highlights its importance not just as a historical site but also as a research hub for underwater archaeology.

Prior to the sanctuary’s designation as a federal preserve, “we had a thing called the human factor,” James says with a hint of irony. “Folks would come out and steal artifacts—they would literally strip them down.” The establishment of the sanctuary has since led to the return of many artifacts, which are now displayed in the Great Lakes Maritime Heritage Center in Alpena.

Despite its rich history and status as a marine sanctuary, Thunder Bay remains a living, breathing part of the community. Local divers, historians, and volunteers are deeply involved in discovering, documenting, and preserving the shipwrecks. This community engagement is vital to the sanctuary’s ongoing conservation and educational efforts.

The sanctuary’s significance extends beyond its borders, forming part of a larger network of marine protected areas across the Great Lakes. This international collaboration between the United States and Canada underscores the importance of preserving the Great Lakes as a shared natural resource.

Whether you’re a history buff, an adventurer, or someone simply looking to connect with the past, Thunder Bay offers an unparalleled opportunity to explore the depths of the Great Lakes in every sense of the word.

“We get up close and personal with some of these shipwrecks,” James says, inviting visitors to experience the sanctuary’s underwater treasures firsthand. Indeed, whether through the glass bottom of a boat or the lens of a diving mask, Thunder Bay’s shipwrecks offer a unique and unforgettable journey into the past.