What is the largest bay on Lake Michigan?

Green Bay is the largest bay on Lake Michigan.

Green Bay is a long, sheltered arm of Lake Michigan extending northward between Wisconsin’s Door Peninsula and Michigan’s Upper Peninsula. It is about 120 miles (190 kilometres) long and has a maximum width of roughly 30 miles (48 kilometres). The bay’s shape provides important natural harbours and protects parts of the shoreline from the full force of Lake Michigan storms.

The city of Green Bay lies at the southern end, where the Fox River enters the bay. The river and surrounding watershed have made the area important for industry, agriculture, shipping, and urban development.

Green Bay is also an ecologically significant water body. Nutrient pollution has contributed to recurring algal blooms, while wetlands and coastal habitats support fish and migratory birds. Green Bay should not be confused with Thunder Bay on Lake Huron or Georgian Bay, a much larger arm of Lake Huron.