Shaped by the Laurentide ice sheet 25,000 years ago, Stellwagen Bank is a terminal moraine, originally located above water. As the ice age receded, rising sea levels made it into an underwater island or plateau, an 842 square mile area that now spans the mouth of the Massachusetts Bay and the Gulf of Maine.
Home to over 500 species of marine life, including more than 70 species of fish, 34 species of seabirds, and 22 species of marine mammals, Stellwagen owes its diversity to its unique location and shape. Deep ocean currents rise as they meet the sharp sides of its plateau, carrying nutrients up to the surface in a process called upwelling. These nutrients attract phytoplankton, and form the basis for a complex organic soup that is the foundation of Stellwagen’s extensive marine food chain.
Stellwagen's rich natural resources have been well known to European explorers since colonial times. Over the centuries, large amounts of groundfish, cod, tuna and even whales have been caught on Stellwagen, sustaining the lives of many commercial fishermen and their families.
Captains of shipping and passenger vessels have also been aware of the Bank, since every ship must pass over it to enter Boston Harbor. Ocean journeys could be hazardous. The coastal steamship Portland is just one of the 18 documented shipwrecks that lies on Stellwagen's floor.
Concerned about possible underwater hazards, the U.S. Navy dispatched Lieutenant Commander Henry Stellwagen to survey and map the area in 1854. In honor of his discovery, the superintendent of the Coast Survey, Alexander Bache, proposed that the Bank be named in his honor.