We have measured blood oxygenation levels in a group of 14 people (8 young people and 6 adults) on a physically demanding expedition to Mt Kenya. Blood oxygenation was measured at 11 different altitudes between 1910 and 4985 m using pulse oximetry. We found that pulse oximetry was suitable for use on a youth expedition and we were able to show that blood oxygenation levels reduced by 6% per 1000 m of ascent. We propose that pulse oximetry could provide a challenging and exciting project as part of a school skiing trip. Such a project could include aspects of physics, physiology, experimental design and statistical analysis in an engaging and stimulating format. (Contains 5 figures.)