The caves are the site of the first cave dives in Britain which were undertaken by Jack Sheppard and Graham Balcombe. Since the 1930s divers have explored the extensive network of chambers developing breathing apparatus and novel techniques in the process. The full extent of the cave system is still unknown with approximately , including 25 chambers, having been explored. Part of the cave system opened as a show cave in 1927 following exploratory work by Herbert E. Balch. As a tourist attraction it has been owned by Madame Tussauds and, most recently, the circus owner Gerry Cottle. The cave is notable for the Witch of Wookey Hole, a roughly human shaped stalagmite that legend says is a witch turned to stone by a monk from Glastonbury. It has also been used as a location for film and television productions, including the "Doctor Who" serial "Revenge of the Cybermen".