Because Michigan weather is unpredictable year round, the state is home to several indoor water parks scattered across the map. READ MORE: Michigan's Biggest Indoor Water Park is Now OpenIn fact, there are two right here in Mid-Michigan less than an hour away from Flint. Frankenmuth is home to both Zehnder’s Splash Village and the newly renovated Bavarian Inn Lodge Water Park, which is now the largest indoor water park in Michigan. Other Indoor Water Parks Across MichiganAccording to Pure Michigan there are close to a dozen indoor water parks that operate year-round, even when it's freezing outside. Michigan Indoor Waterparks Avalanche Bay Indoor Waterpark (Boyne Falls): Michigan’s largest indoor waterpark, featuring 5 slides, a lazy river, and a surf simulator.