I have set myself the challenge of climbing the highest mountain on each of the world's seven continents to raise money for Great Ormond Street Children's Hospital. The mountaineering challenge to climb the Seven Summits is traditionally based on either the Bass (which includes Kosciusko, the highest Australian summit) or the Messner list (which includes the Carstensz Pyramid in Papua, Indonesia). In world history, only 105 climbers have ever climbed all the eight peaks required to complete both lists. The Seven Summits gives a focus to mountaineers worldwide, but the demands placed on fitness, the physical hardship, the dangers to overcome and the outlay in both time and money are too extreme for most to complete. To summit these eight mountains is an exceptional test of ability and dedication, requiring the mountaineer to travel and climb in every corner of the globe.

After successfully summiting Mount Kilimanjaro (5,895 m, 19,341 ft) in September 2010, I have now joined a 25 day expedition to Aconcagua, a peak of 6,962 m (22,841 ft), located in the Andes mountain range of Argentina. The effects of altitude will be severe as atmospheric pressure is 40% of that of sea-level at the summit. It will be an enormous undertaking, as Aconcagua is plagued by strong winds (100km/hr or greater), extreme cold (wind chill to -40) and snowstorms high on the mountain.

Please join me in raising money for Great Ormond Street Children's Hospital by sponsoring my climb to the summit of Aconcagua, the highest mountain in the world outside of the Himalayas. (100% of your donations go to Great Ormond Street Hospital.) Sponsors will all receive an expedition report on my return to the UK.

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So please dig deep and donate now.