Big Bay is an unincorporated community in Marquette County of the U.S. state of Michigan. It is a census-designated place (CDP) for statistical purposes and does not have any legal status as an incorporated municipality. As of the 2000 census, the CDP population was 265. The community is located within Powell Township near the shore of "Big Bay" on Lake Superior.
Although the Big Bay community is served by the Marquette ZIP code 49855, the Big Bay post office with ZIP code 49808, serves a much larger area to the west and south of the community and CDP, including portions of Powell Township as well as Ishpeming, Champion, Michigamme, and Ely townships.