Lake Vermilion-Soudan Underground Mine State Park facts for kids
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Soudan Iron Mine
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The 27th level of the Soudan Mine
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 Location in Minnesota
Location in the United States
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| Location | Tower-Soudan State Park, Breitung Township, St. Louis County, Minnesota |
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| Nearest city | Tower, Minnesota |
| Area | 122 hectares (301 acres) |
| Built | 1900 |
| Website | Lake Vermilion-Soudan Underground Mine State Park |
| NRHP reference No. | 66000905 |
Quick facts for kids Significant dates |
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| Added to NRHP | November 13, 1966 |
| Designated NHL | November 13, 1966 |
The Lake Vermilion-Soudan Underground Mine State Park is a special place in Minnesota. It's home to the Soudan Underground Mine, which is on the south shore of Lake Vermilion. This mine is famous for being Minnesota's oldest, deepest, and richest iron mine. It was also once a site for important science experiments. The mine is so important that it's recognized as a U.S. National Historic Landmark.
Contents
Discovering Iron at Soudan
In the late 1800s, people were looking for gold in northern Minnesota. Instead, they found something even more valuable: huge amounts of iron! This iron was called hematite and was very pure, with more than 65% iron.
From Open Pit to Deep Underground
Mining started in 1882 with an open pit, which is like a big hole in the ground. By 1900, miners began digging underground tunnels. This was a safer way to get the iron out. The United States Steel Corporation owned the mine from 1901 until it closed in 1962.
How Deep Did They Go?
By 1912, the mine was already 1,250 feet (381 meters) deep. When it closed, the deepest part, called level 27, was 2,341 feet (713.5 meters) below the surface. Imagine, the underground tunnels stretched for more than fifty miles! In 1965, the mine was given to the State of Minnesota. It became a park where people could learn about mining history.
Smart Mining Techniques
The miners used a special method called "cut and fill." They would dig out the ceiling and then fill the space below with waste rock. This kept the floor and ceiling always about 10–20 feet (3–6 meters) apart. It was a clever way to mine because they didn't have to bring all the waste rock to the surface. This method worked well because the iron rock at Soudan was very strong.
Visiting the State Park
The park is located in Breitung Township, Minnesota, right on the beautiful Lake Vermilion. It's a popular spot for tourists, especially those heading to Ely, Minnesota or the Boundary Waters Canoe Area Wilderness.
A National Historic Landmark
The Minnesota Department of Natural Resources manages the park. Because it's a National Historic Landmark, it's also listed on the National Register of Historic Places. This means it's a very important historical site in the U.S.
Mine Tours and History
You can visit the surface buildings of the park. During the summer, you can even take tours deep into the mine! Visitors ride an old electric mine hoist from 1924 down to level 27. This is the lowest level, 2,341 feet (713.5 meters) underground. As of 2025, tours of the underground science lab are not available.
Two Parks Become One
The Soudan Underground Mine State Park used to be separate from Lake Vermilion State Park. In 2010, Minnesota bought about 3,000 acres from U.S. Steel to create Lake Vermilion State Park. This new park included the Stuntz Bay Boathouse Historic District. In 2014, these two nearby parks joined together to become one big state park.
Underground Science Lab
In the 1980s, scientists from the University of Minnesota started using the deep mine for special physics experiments. The mine was perfect because it was so deep underground. This depth blocked most cosmic rays, which are tiny particles from space that can mess up sensitive experiments. Also, they could use the mine's working hoist, which saved money.
Experiments in the Deep
The lab was home to experiments like Soudan 1 and Soudan 2, which looked for something called proton decay. Later, bigger projects came along, such as the MINOS neutrino detector. Scientists also searched for dark matter with experiments like CDMS-II, SuperCDMS, and CoGeNT. They even worked on making super-pure copper for other experiments. The mine was considered for a big U.S. science lab, but another mine in South Dakota was chosen instead. The underground lab and its public tours closed around 2016.
Mine Challenges
2011 Fire Incident
On March 17, 2011, a fire started deep in the main shaft on the 25th level. Firefighters used 70,000 gallons of foam to put it out. The foam filled the lowest level of the shaft. The underground lab lost power but stayed safe. Mine tours were closed for that summer, but above-ground tours reopened. After a lot of cleaning, underground tours started again on May 26, 2012.
2024 Flooding Event
After very heavy rain on June 18, 2024, the Soudan Mine flooded. A lot of water rushed into the mine. There was also damage to the underground lab's air conditioning, the pump system, and the electrical system. Several trains inside the mine were also damaged. Because of this flooding, underground tours are still closed as of August 2025.
See also
