The aim of this study was to develop an in-depth understanding of the beliefs parents hold regarding portable pool safety behaviours using the theory of planned behaviour (TPB). Semi-structured interviews were conducted with parents (N = 15) of children aged 5 years and younger who owned a portable pool. Interviews examined three key safety behaviours: supervising within arms' reach, fencing portable pools deeper than 30 cm, and emptying and storing portable pools safely after use. Parents identified a range of advantages, disadvantages, normative influences, and facilitators and barriers towards the three behaviours. The identification of these salient behavioural, normative, and control beliefs enrich limited understandings of portable pool safety behaviours of parents with young children. Current findings fill a knowledge gap in portable pool safety and provide potential targets for messages to improve parents' behaviours for their young children around portable pools in the hope of preventing loss of life.