At 8000 m and above, a ‘death zone’ reputation afforded protection for the fragile ecosystems of the Himalaya and Korakoram ranges for thousands of years. After decades of high-altitude mountaineering, environmental impacts have been documented such as associated carbon-intensive air travel and contamination from waste. Despite the growing popularity, high-risk and fragile context of the sport, the behaviour, perspectives and experiences of high-altitude mountaineers, and the social and economic consequences have not been researched. Following an interpretive paradigm and using purposive sampling, this qualitative study conducted in-depth interviews and open-ended survey questions to collect the experiences of sixteen high-altitude mountaineers. Analysis of the qualitative data was informed by Grounded Theory with the coding process leading to the overarching category of ‘leave no trace’. The results show how the high risks to life, and growing popularity of the activity influence mountaineer’s ability to act sustainably and increase unsustainable behaviour despite a desire to ‘leave no trace’ on the mountain. Meanwhile, climate change has already and will increasingly have profound impacts on the risks associated with 8000m mountaineering. Allowing more time for acclimation would help to address the root causes of unsustainable behaviours along with better enforcement of regulations.