Big Bay is an unincorporated community located in Marquette County in the U.S. state of Michigan. Situated on the shore of the eponymous bay of Lake Superior, the community lies within Marquette Township approximately 14 mi (23 km) northeast of the city of Marquette, the county seat. The geographic coordinates of Big Bay are roughly 46°52′N latitude and 87°23′W longitude, at an elevation of about 620 feet (190 m) above sea level.
The area is primarily residential and serves as a gateway to recreational sites such as Big Bay State Park, which offers camping, hiking, and shoreline access. The community is accessed mainly via US Highway 41/M‑28, which runs along the Lake Superior shoreline.
Big Bay does not have a separate municipal government and is governed at the township level by Marquette Township authorities. Population figures are not reported separately in the U.S. Census; demographic data for the community are incorporated within broader township statistics. Postal services for Big Bay use the ZIP code 49814, which is assigned to the nearby city of Marquette.
Historically, the name “Big Bay” derives from the large inlet of Lake Superior that it borders, a geographic feature noted on early 19th‑century maps and used by both Indigenous peoples and European‑American settlers. The community developed in the late 1800s as part of the regional expansion tied to mining, logging, and transportation along the Great Lakes shoreline.
Education for residents of Big Bay is provided by the Marquette Area Public Schools district, and the community is within the service area of the Marquette Regional Medical Center.
As an unincorporated locality, Big Bay lacks defined boundaries and its extent is generally understood through local usage and the area covered by the postal designation.