BlueSpring Caverns

Located in southern Indiana, this cave is one of the most unique caves in the United States. The entire cave tour takes place in a boat! Outside the cave, there is a half mile trail outside the cave to see the sinkhole that led to the cave's discovery. Depending on how high the water is, you might have to duck your head as you pass through some of the shorter passages.

Photo Credit https://www.exploresouthernindiana.com/