Discover Alpena: A Pure Michigan Itinerary

Alpena Lighthouse on Thunder Bay

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The Alpena area has one of the nation’s highest concentrations of sinkholes. These natural features are created when a layer of anhydrite and gypsum dissolves away from under the ground’s surface, causing it to collapse and leaving a depression in the land. You can visit these natural wonders in lush forests and see some of the unique plant life that may grow in microbiomes at the bottom of the sinkhole—some of which are deeper than 100 feet!

Please remember to practice extreme caution when navigating the area around sinkholes. Learn more