Rebecca began doing adventurous expeditions shortly after her marriage to John, with an expedition to the north face of Mount Everest on which she rescued John from a crevasse that he fell into, high on the Main Rongbuk Glacier at an altitude of around 6,250 metres.
On 21st May 2005 Rebecca attempted her first speed climb of Kilimanjaro, starting from Marangu Gate at around noon, following some administrative delays imposed by the park authorities. She summited Kilimanjaro in the middle of the night; a little before 0200, in high winds and a snow storm. While the men’s record is attempted on an almost annual basis, Rebecca's record stood for four years before being beaten.
Rebecca’s attempt was a timed ascent only, and she walked down the mountain.