In Michigan’s Upper Peninsula along the scenic southern shore of Lake Superior lies a unique piece of Michigan’s iron ore history. Nestled within the Hiawatha National Forest just west of Munising you will find the crumbling ruins of Bay Furnace. One of only two remaining blast furnaces in the Upper Peninsula, Bay Furnace was used to make pig iron between 1870 and 1877. If you’re visiting the Upper Peninsula, traveling along M-28 in the U.P., Bay Furnace Historic Site is a scenic stop that offers a window into Michigan’s past.
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Topography of the Region
The maps below highlight the topography of the Hiawatha National Forest and Superior’s southern shore. Note Grand Island immediately to the north of the town of Christmas. The beach at Bay Furnace offers a clear view of Grand Island. As you have time to explore, Grand Island National Recreation Area is a beautiful natural area worth visiting. At 13,500 acres, Grand Island has something for everyone, including backcountry camping, 40+ miles of mountain biking and hiking trails, and beautiful, quiet beaches. Access Grand Island via the Grand Island Ferry Service or by personal watercraft.
Bay Furnace Location & Directions
From Munising, drive 5 miles west along M-28 to Bay Furnace. From the town of Christmas, drive 5 miles east to M-28; head north for 0.3 miles to enter the campground and Historic Site. M-28 is the main highway in this area, and the site is marked by a large road sign, so it’s hard to miss!
Historic Site, Interpretive Trail & Campground
Within the Historic Site, enjoy a hike along a short, 0.8 mile, wheelchair accessible interpretive trail around the grounds. Additionally, Bay Furnace Campground is available for reservations with 49 sites, a swimming beach, and frequent sightings of the Northern Lights.
Slag & the Smelting Process
If you’re familiar with the iron ore smelting process, you may have heard of slag. This unique byproduct of the pig iron smelting process forms during the melting of iron ore. To bind with impurities in the iron ore like sillica, limestone was added during the smelting process. This surplus was lighter than the surrounding liquid iron ore, floating to the top. The resultant “waste” was often dumped directly into the cold waters of Lake Superior. Due to the quick cooling that Lake Superior provided, slag formed into a smooth, glassy textured byproduct that can be found on this beach today.
Bay Furnace | A Brief Operation
When the blast furnace ceased operations in 1877, the excess slag was dumped along the Lake Superior shore. As you walk the beach at Bay Furnace, you can find pieces of slag buried in the sand. Over the years I have found varied colors of slag from a milky blue to gray, green, purple, and black. My favorite pieces are those with swirled colors from the blended cooling of different minerals. As you can see in the photos below, some pieces are more glassy and opaque, similar to obsidian, while others are more vesicular in texture. It’s fun to dig around for these unique pieces of Michigan’s history.
Au Train Beach
Additionally, this quiet stretch of Superior shore is located at the mouth of the Au Train River. It is a beautiful stop to swim or just enjoy the view along M-28; read more in my recent article: Visit Lake Superior’s Scenic Au Train Beach.
Bay Furnace | AllTrails Maps
If you’re looking for nearby hikes a bit longer than the brief loop around Bay Furnace, consider hiking in the Pictured Rocks National Lakeshore in nearby Munising. For detailed information on the best forested trails in Pictured Rocks, explore over 500,00+ trail on AllTrails. Search by trail type, with photos, maps, and detailed trail reviews.
Muldoons Pasties
If you pass through Munising, be sure to stop at Muldoon’s Pasties in Munising for a pasty with gravy (best in the UP, in my humble opinion!). Muldoon’s Pasties and Gifts is located at 1146 M-28 West in Munising. Pasties available are beef, chicken, and vegetable. Muldoon’s also offers dessert pasties! (cherry, blueberry, raspberry, and strawberry, and seasonally, pumpkin!)
Pictured Rocks National Lakeshore
In nearby Munising, there are miles of trails to explore in Pictured Rocks National Lakeshore. A visit to this beautiful stretch of Superior shoreline will not disappoint, whether you plan to hike, camp, swim, boat, or just enjoy the scenery. For a unique adventure by boat, you can book a seat on the Pictured Rocks Cruises to take in this beautiful area. Read more in my recent article: Experience Pictured Rocks National Lakeshore | Stunning Lake Superior Views.
Marquette, Michigan | Nearby Adventures
For more information on outdoor recreation, great restaurants, culture, and unique lodging options in neighboring Marquette, read more in my 2026 Adventure Guide: Recreation, Culture, and Food in Marquette, Michigan.
Your time along the Lake Superior shore will leave you with a new appreciation for the vast beauty of our beautiful Great Lakes. Recreation, history, beautiful beaches and vast views. Enjoy your visit to Bay Furnace Historic Site and exploration of Lake Superior’s southern shore!
-Erin
My daughter has property in the UP, and it’s her happy place.