Back to Sid's filmography: This film is dedicated to Otter Hole, the entrance of which is on the banks of the River Wye, near Chepstow. Otter Hole is notorious for its tidal sump and ubiquitous mud in the entrance series, and renowned for its beautifully decorated passages in the upper series. The first half of the film is an account of the original exploration of the cave, and the second part shows an attempt to push the end of the cave towards its sinks at Itton. Much of the filming was done during a five day session which involved camping in the far reaches, and a mile of cable being run through the cave to allow lighting batteries to be recharged. Cavers featured include Dave Parker, Phil Schwartz, John Elliott, Paul Taylor, Diana Court, Ian Standing, and Claire Bishop. The film was first broadcast on Channel 4 on 18th November 1984.