Pure Michigan Minute VIDEO: Since 1847, a lighthouse has been located at DeTour Passage at the northwestern head of Lake Huron. Originally placed on shore at Point DeTour, Michigan, the Light was moved offshore to DeTour Reef in 1931. The Light marks the mouth of the St. Mary's River, which connects Lake Huron to Lake Superior. It is well known to ship captains and pleasure boaters who sail the upper Great Lakes. For generations the Light at DeTour Passage has provided a beacon for those vessels seeking the "Gateway to Superior”.