Outdoor swimming for both leisure and physical exercise is a fast-growing activity in the United Kingdom. However, research into the perceived effects of outdoor open water swimming on psychological well-being is limited. Considering the inherent combination of physical activity, leisure, and nature immersion, the notion of outdoor swimming as a potential activity in the social prescribing initiative to enhance psychological well-being was investigated. Guided by Ryff's (1989) six core dimensions of psychological well-being, ten swimmers who frequently swim recreationally in the sea (n = 5) or freshwater bodies (n = 5) around the UK were interviewed via Microsoft teams. Interviews explored the perceived influence of recreational outdoor swimming in the sea and in freshwater bodies on swimmers' psychological well-being. Interview data were analysed using reflexive thematic analysis. A combination of inductive and deductive analytic approaches enabled findings pertaining to the six dimensions of PWB to be identified (deductive analysis), as well as novel findings (inductive analysis) derived from the data through open coding. Two broad themes were identified following inductive analysis, motivation and enablement. Motivation to swim outdoors aligned with social prescribing objectives, including swimming for leisure, exercise, time alone, company, and connection to nature. Findings also indicated the enablement of emotional regulation through meditation, reflection, and escape when outdoor swimming. It enabled pain relief through cold water exposure, and psychological well-being aligned with the six dimensions outlined by Ryff (1989). Findings illustrate the potential benefits of outdoor open water swimming for psychological well-being and its possible utility in the social prescribing agenda.