ABSTRACT This study aimed to explore the experiences of a nature-based outdoor activity program for children and adolescents who have survived a serious illness like cancer, as well as their siblings. The study utilised individual semi-structured interviews (N=10) and focus group interviews (N=8) to investigate the experiences of participants, parents, and program leaders. Data was analysed using interpretative phenomenological analysis (IPA), resulting in two main themes: 1) What nature affords, and 2) Influence on the child. The various affordances in nature influenced the child in multifaceted ways: mastery experiences, autonomy, motivation, awareness, stress reduction and affect regulation, belongingness and social support. These categories are connected to the main agentic features: intentionality, forethought, self-reactiveness and self-reflectiveness. The Nature school contributes to the development of agency within children. They become more capable of self-care, and there are examples of the children transferring this knowledge to other aspects of their daily lives.