Name and Location

The Round Island Passage Lighthouse, also known as the "Round Island Passage Light," has guided vessels through the treacherous channel between Mackinac Island and Round Island since 1895. It is located at R9VM+6R Mackinac Island, MI, USA, with coordinates 45°50′35″ N, 84°36′55″ W.

2. Construction and History

The lighthouse was constructed in 1895 to mark the southern edge of the Round Island Channel in Lake Huron. It has been listed on the National Register of Historic Places since August 6, 2013. The purpose of the lighthouse is to replace earlier, less-visible lights and warn mariners of shoals, ensuring safe passage on one of the busiest Great Lakes corridors.

3. Architecture and Materials

The lighthouse features late 19th-century utilitarian architecture, combining brick and cast-iron elements on a concrete crib foundation. The materials used include brick-clad cast-iron tower rising from a rectangular concrete pier, with an overall structure standing at approximately 42 ft tall, supported by a crib in 33 ft of water.

4. Light and Navigation

The original lens was a Fourth-order Fresnel lens (now removed), replaced by a modern acrylic beacon. The focal height is approximately 60 ft above lake level, with a nominal range of 9 nautical miles (statutory). The characteristic is flashing White every 10 seconds (Fl W 10s). The lighthouse is fully automated and de-staffed since the mid-20th century.

5. Accessibility and Visiting

Visitors can reach the lighthouse only by private boat, as there is no public dock or on-shore access. Climbing the tower is not permitted. Guided visits are not officially offered; best viewed from passenger ferries to Mackinac Island or private charter vessels.

6. Notable Views and Landscape

The lighthouse provides a panoramic sweep of the Straits of Mackinac, the distant silhouette of Mackinac Island's Grand Hotel, and, to the north, the iconic suspension span of the Mackinac Bridge.

7. Anecdotes and Folklore

Local lore holds that during storms the light's keeper once waded ankle-deep in the frozen cribhouse, tending the lens by lantern lamp (speculative anecdote). Photographers prize the site at dawn and dusk for dramatic skies and water reflections.

8. Technical and Operational Details

The managing authority is the U.S. Coast Guard, Ninth District (Great Lakes), with the function of an active navigational aid and marker light for offshore passage. The nautical chart reference is NOAA Chart 14823.

9. Further Information

For further information, please refer to the National Register of Historic Places Nomination Form, Ref. #13000583; U.S. Coast Guard Light List, Volume V: Great Lakes (current edition); "Round Island Passage Light," Wikipedia: https://en.wikipedia.org/wiki/Round_Island_Passage_Light; and NOAA Nautical Chart 14823.