Footage of the Buffalo Reef in Lake Superior / GLIFWC via YouTube Footage of the Buffalo Reef in Lake Superior / GLIFWC via YouTube loading...What is a reef? While there are natural and artificial reefs in Lake Michigan and other Great Lakes, Lake Michigan's four largest reefs, known as the Midlake Reef Complex, are natural. The Milwaukee Reef, described as "the most important geological formation" in Lake Michigan, runs from Milwaukee to a point between Grand Haven and Muskegon. There isn't much information about the Milwaukee Reef itself, but the Midlake Reef Complex plays a vital role in Lake Michigan. These Very Special Streets Run Directly Along the Coast of Lake Michigan From the Indiana state line to the Straits of Mackinac there are special roads that hug the coast of Lake Michigan from big cities to small towns.