Minnesota's Once-Thriving Mines Transformed Into The State's Deepest Inland Lake With Crystal-Clear Water

Minnesota is known for its lakes — although the state is called the Land of 10,000 Lakes, there are actually 11,842 lakes here. One way to experience the state's unique lakes is by visiting central Minnesota and discovering the deepest inland lake in the state: The Mahnomen, Alstead, and Arco Mine Lake Chain. These lakes were once part of the state's booming mining industry in the Cuyuna Range. Today, they offer opportunities for outdoor recreation in super-clear water.

The Cuyuna Range was once home to 27 iron ore mines during its heyday. It had the biggest supply of manganese-rich ore in the U.S., which was in high demand during World War II and the Korean War. In 1953, production in Cuyuna reached an impressive 3.5 million tons. However, mines started closing in the 1960s, and the last shipment of iron ore from Cuyuna was in 1982. Most of the mines were open pits, and they filled with water, creating deep lakes.

The Mahnomen, Alstead, and Arco Mine Lake Chain is 525 feet deep, making it the deepest inland lake in the state. This set of lakes covers 272 acres with 8 miles of shoreline and is popular for fun water activities. No speedboats are allowed here, but swimming, paddleboarding, and kayaking are all great ways to get out on the water. It's best to go on a still or calm day with no wind — rent kayaks, paddleboards, or canoes from Cuyana Outfitters in the Midwest gem of Crosby.

The shimmering, crystal-clear water here is a special characteristic of this chain of lakes. The lakes can have spectacular blue-green water that's super clear and surrounded by forest. Visibility ranges from 30 to 90 feet, making it "some of the best scuba diving Minnesota has to offer," according to one Tripadvisor reviewer. Divers can see sheer walls, submerged mine shafts, underwater forests, mine roads, railroads, and other vestiges of the once-thriving mining industry. It's possible for divers to rent equipment and get local advice from Minnesota School of Diving in Brainerd, the heart of Minnesota's lake country, which is just 20 minutes away.

Mahnomen, Alstead, and Arco Mine Lake Chain is in the Cuyuna region, just minutes from Crosby in central Minnesota. It's about a 2-hour drive north from Minneapolis — while there are airports in Brainerd Lakes and Duluth, the most convenient major airport is Minneapolis-St. Paul International Airport (MSP), just under a 2.5-hour drive. Don't miss the chance to explore the sunny swim beaches at Portsmouth Mine Lake while in the area.