Potagannissing Bay is a shallow, island-strewn bay on Lake Huron in Algoma District, Ontario, Canada and Chippewa County, Michigan, United States. It is bounded by the land masses of St. Joseph Island, Ontario at the northwest and Drummond Island, Michigan at the southeast, and by the water bodies the Saint Marys River and the De Tour Passage at the southwest and the North Channel at the northeast. The bay is northeast of De Tour Village, Chippewa County.