BBC Ultimate Caving

Kate Humble attempts one of the most extreme of all extreme sports, played out in a terrifying place. Difficult, dangerous, physical, it's most people's idea of sheer hell. For her, this will be a completely new, and at times horrific experience - a journey into Britain's underworld - a land of daring, adventure and beauty.

Kate will attempt four distinct and increasingly difficult caves. Each cave will push her further and further, testing her courage, determination and stamina. In her final cave, she will have to attempt a vertical ascent on ropes out of a cavern which is higher than the London Eye. This is a mission that will demand new levels of courage, determination and stamina from Kate - can she rise to the challenge? Or will it break her?

BBC Ultimate Caving Series Full details from the BBC: