This study examines decision making in outdoor recreation extreme events, through the example of Britain's National Three Peaks Challenge. This nature-based tourist activity requires hiking Scotland's, England's and Wales's highest mountain in 24-h. Drawing from naturalistic decision making theory and behavioural economics, critical discursive psychology is used to propose an alternative way of viewing decision making by arguing that it is a socially constructed phenomenon; one that is continually managed and negotiated in response to the unpredictability of the mountains and dynamics of the walking group. Eleven semi-structured interviews with Three Peak Challengers and stakeholders were conducted to explore their perceptions and experiences of the challenge, and motivations for taking part. Data were analysed using critical discursive psychology in order to examine how decision making and rationality were socially and discursively produced. Three interpretative repertoires were identified: (1) positioning walkers as vulnerable (2) sharing accountability as a function of decision making, and (3) constructing questionable judgements. The findings show how the irrational push of outdoor recreation extreme events calls into question the extent to which rationality and good decision making is possible, illustrating the dilemmas that participants must resolve if they are to have a successful challenge. As participants are often inexperienced mountain walkers, the need for professional guides to lead such unique recreational activities is therefore reinforced. The analysis also raises broader issues for how we understand the nature of human decision making in extreme situations.