Inside the spectacular cave under a city's streets
A rare glimpse inside a spectacular secret cave under the streets of suburban Bristol.
Pen Park Hole is a natural wonder which was recently declared a Site of Special Scientific Interest (SSSI).
At street level, you would not know it existed because it is hidden 25 metres under Southmead on the edge of Bristol.
BBC Inside Out has been given a rare opportunity to see inside the cave with a group of intrepid explorers.
Linda Wilson from the University of Bristol and Chris Westcott from Natural England also provide an insight into the natural history of the cave.