Surf therapy is a novel intervention that has been shown to have positive effects on youth mental health and associated downstream negative effects on social, physical and occupational functioning. While the evidence-base on the effectiveness of surf therapy to improve youth mental health is emerging, to date there is little published evidence outlining program development or potential mechanisms and pathways to positive change. Intervention mapping is a method often used in program development in other health fields. The intervention mapping protocol outlined by Bartholomew Eldredge and colleagues (2016) describes an iterative process that allows program developers to identify and then solve complex problems, leading to program development. The protocol involves six steps: 1) Needs assessment, 2) Formulation of change objectives, 3) Selection of theory?based methods and practical strategies, 4) Development of the intervention, 5) Adoption and implementation plan, and 6) Evaluation planning. This study aims to describe the intervention mapping protocol and apply it to the development and refinement of a novel surf therapy intervention, Ocean Mind. The Ocean Mind program combines psychoeducation, water safety and learn-to-surf activities with the overall program objective to improve mental health among child and adolescent participants. Based on the steps of intervention mapping, theory-based methods and strategies were selected that informed the activities of the intervention and these were applied at the level of the individual and environment. This process led to a theory and evidence informed surf therapy program adapted to the local Australian context. While intervention mapping has been criticized for being time-consuming and burdensome, the resulting outcome may lead to increased effectiveness. It is hoped that the matrices of change objectives presented in the current work will assist future surf therapy program developers to design, implement and evaluate surf therapy interventions using a similar systematic approach.