Seneca Caverns (Ohio)

Seneca Caverns is a show cave located in northeastern Seneca County, Ohio, USA, just outside Flat Rock. The cave is designated as a Registered Natural Landmark by the Ohio Department of Natural Resources.
History.
The cave was discovered in June 1872 by two boys named Peter Rutan and Henry Homer while they were hunting rabbits with their dog. The dog chased a rabbit into a brush pile, where they then disappeared. While searching through the brush pile, the two boys found an opening, fell through it, and landed in the first level of the cave, where they found their dog. The boys returned home and told everyone about their discovery. The cave became known as Good's Cave, named for Emmanuel Good, the owner of the farm on which the cave was located.
In 1931, Don Bell, a lawyer from Bellevue, discovered a series of passageways and rooms in the cave which led to an underground river, called Ole' Mist'ry River, which is part of the vast groundwater system that underlies the surrounding region. After two and a half years of improvement effort, the cave was renamed Seneca Caverns and opened to the public on May 14, 1933.
Levels.
There are 7 levels that are open to the public 
There are lower levels that have only been explored during severe droughts 