Mammoth Cave National Park in Kentucky is the world's largest cave system. There are over 367 miles of mapped cave. Most visitors come for one of the many cave tours offered throughout the day, but you can also hike, camp, ride a mountain bike, ride a horse, or canoe one of the rivers.

The shortest cave tour is the Frozen Niagara Tour. If you have slightly more time, take one of the Historic Tours that go through the historic entrance to the park. There are also other tours offered throughout the day, depending on which season it is. If you know you are going to be at the park at a certain time, or if there is a tour you are particularly interested in, reserve it in advance at (877)444-6777.

If you are feeling adventurous, take the Wild Cave Tour - you will need to dress appropriately, with over the ankle boots, gloves and long pants, and kneepads. You will also need a full day, as the trip takes six and a half hours. You will get muddy, and you will have to pass through 9-inch tall passages.