St. Martin Island Light stands on St. Martin Island, Michigan, marking one of the four passages between Lake Michigan and Green Bay. Built in 1905, it is notable as the only pure exoskeletal tower on the Great Lakes in the United States, with a white hexagonal iron structure supported by six exterior steel posts and latticed buttresses. Its station included first a steam fog signal and later a diaphone, underscoring the passage’s navigational importance in all conditions. The cream city brick keeper’s house was modeled after the Plum Island Range Lights dwelling. The station was added to the National Register of Historic Places in 1984 and is managed with the Little Traverse Bay Band of the Odawa Indian Nation.