This site is open to the public.
it consists of a horizontal lead miners' adit (a level passageway driven horizontally into the hillside) leading to the cavern itself, a natural limestone cave. The adit is permanently flooded, resulting in Speedwell Cavern’s (locally unique) feature: after descending a long staircase, the visitor makes the journey into the cave by boat. Originally the guide propelled the boat by pushing against the walls with his hands, later the boat was legged through, and now it is powered by an electric motor.
At the end of the adit, the visitor alights from the boat and walks into the cave to see the fluorspar veins, the stalactites and stalagmites, and the so-called “Bottomless Pit”. This pit is an extremely deep vertical shaft