An Adelaide mother-of-three has become the first woman in the world to complete the death-defying Seven-Seven challenge. Mountaineer Katie Sarah has now summited not only the highest mountain on every continent, but also the seven highest volcanic peaks – a feat referred to in mountaineering as the ‘Seven-Seven’. The 49-year-old became the eighth person to join the elite – previously men’s only – club when she successfully summitted Mount Sidley in Antarctica on January 14.