Thunder Bay National Marine Sanctuary

Thunder Bay National Marine Sanctuary and Underwater Preserve
Location among Michigan's Underwater Preserves
Location	Lake Huron (Alcona, Alpena, and Presque Isle counties, Michigan)
Nearest city	Alpena, Michigan
Coordinates	45°00′12″N 83°15′11″W / 45.0034°N 83.253°W / 45.0034; -83.253Coordinates: 45°00′12″N 83°15′11″W / 45.0034°N 83.253°W / 45.0034; -83.253
Area	4,300 sq mi (11,000 km2)
Established	2000
Governing body	Michigan Department of Natural Resources, National Oceanic and Atmospheric Administration

Thunder Bay National Marine Sanctuary and Underwater Preserve is a United States National Marine Sanctuary on Lake Huron, within the northeastern region of the U.S. state of Michigan. It protects an estimated 116 historically significant shipwrecks ranging from nineteenth-century wooden side-wheelers to twentieth-century steel-hulled steamers. There are a great many wrecks in the sanctuary, and their preservation and protection is a concern for national policymakers. The landward boundary of the sanctuary extends from the western boundary of Presque Isle County to the southern boundary of Alcona County. The sanctuary extends east from the lakeshore to the international border. Alpena is the largest city in the area.

The National Oceanic and Atmospheric Administration established Thunder Bay National Marine Sanctuary and Underwater Preserve in 2000. It became the thirteenth overall and first on the Great Lakes. Original boundaries followed that of Alpena County to 83 degrees west longitude totaling 448-square-mile (1,160 km²). In 2014 it was expanded to 4,300-square-mile (11,000 km²). The marine sanctuary contains many shipwrecks, such as the hull of package freighter SS Pewabic.

Tied to the sanctuary is the Great Lakes Maritime Heritage Center. The museum, located in Alpena on the Thunder Bay River, features exhibits about local shipwrecks and the Great Lakes, an auditorium, an archaeological conservation lab, and education areas.