Mammoth Cave National Park is not located in the state of Michigan, but rather in Kentucky. It is the world's longest known cave system, with over 400 miles explored and mapped. There are several reasons to visit the park, including the opportunity to explore the caves through guided tours, hike through the surrounding forest and river valley, and participate in various outdoor activities such as camping and wildlife viewing. Points of interest include the historic entrance, the Frozen Niagara formation, and the underground river. Interesting facts about the area include the diversity of plant and animal life, including several endangered species, and the rich history of human use of the caves. The best time of year to visit is during the summer and fall months, when the weather is mild and the park offers a variety of activities and events.