<p>Participation in nature-based and adventure sports has been reported to increase pro-environmental behaviours and attitudes amongst participants. However, travel for sports participation has been shown to increase an individual’s carbon footprint, highlighting a "value-action" gap. The environmental impacts of sports-related clothing and equipment production have not been extensively studied, meaning that the true environmental costs of sports participation are underestimated. In this study, the clothing and equipment ownership of UK water-sports participants (n=320) were quantified and extrapolated to the UK population, building a baseline estimate of the volumes of clothing and equipment extant in the UK. This was bolstered by streamlined life cycle assessments of the production phase of a range of dinghy and yacht sails. Participants engaged in a broad range of water-sports and demonstrated diverse ownership and usage patterns. Those engaging most frequently tended to own significantly higher quantities of clothing and equipment. For these participants, the environmental impact of equipment purchases - particularly sails - can outweigh that of sports-related travel. For example, the production of a single carbon fibre composite sail may to emit 974.95 kgCO<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(_{2-e}\)</EquationSource> </InlineEquation>, surpassing the estimated annual transport-related emissions for an individual water-sports participant. These findings highlight the need for better data on equipment and clothing ownership and participant behaviours. By addressing this gap, this research contributes to understanding sustainable practices in the water-sports sector and provides insights that can inform future approaches for industry and policymakers, supporting a circular economy for sports clothing and equipment.</p>