|This cave was opened by the quarrying operation in 1847 and was visited by nineteenth-century cave scientists. Between the wars it was frequently used by local people and most of the formations inside the cave have now been destroyed. The quarry has been closed for many years and has now been filled in and leveled. Access to the cave system is maintained by a 16m shaft. The cave is the largest in Devon, the passages having a total length of 3.5km. The system is quite complicated in that it consists of chambers and passages at various levels. The cave is still being actively developed by a stream that runs through a part of the system and flows on to the River Dart. The cave system largely runs beneath the church and the churchyard. The cave is used by cavers for sporting purposes and access is controlled by the Devon Cave Rescue Organisation.
||The First Chamber, a boulder-strewn hall up to 7m high and nearly 50m long, has a small stream flowing at the bottom of it. This stream can be traced at various points in the cave. A bedding plane passage at the end of First Chamber leads via Boulder Hall extension to Crystal Corridor and some muddy passages. Also at the end of First Chamber is a route to the left that leads, via Dutch Oven Tunnel, a passage with a circular cross section, to the Glorious Devon Series. This is a part of the Lower Stream Series which begins in Judges Chamber which is some 7m high, 8m wide and 15m long. In 1967 members of the PCG discovered an important extension now known as the Upper Series. About a kilometre in length it contains a large chamber, Plymouth Chamber, over 30m long and 5m wide.