Background Childhood, adolescent and young-adult (AYA) cancer survivors often experience health problems due to late or long-term effects of their cancer or the treatment thereof. The general population gains health benefits from immersion in nature, and nature-based programmes seem to be an intervention that can promote health among childhood and AYA cancer survivors. Objective To explore the impact of the WAYA wilderness programme on the health of childhood and AYA cancer survivors. Methods The study had a qualitative approach, with data from individual interviews (n = 18) 3 months after completion of the WAYA programme. In addition, case report data was collected during follow-up talks (1, 2 and 12 months after the programme) (n = 19). The WAYA programme consisted of an 8-day expedition, followed 3 months later by a 4-day base camp. The programme included activities such as hiking, backpacking, kayaking, rock climbing, bushcraft and mindfulness. Data was analysed according to a qualitative content analysis. The consolidated criteria for reporting qualitative research (COREQ) were followed. Results An overarching theme was identified: “Personal growth from challenges in nature supported by deep connections with others”. In 4 additional themes, participants’ experiences describe how deep personal connections arose, as they developed a feeling of being able and competent in nature. Nature provided a space that supported relaxation and respite from everyday challenges and stimuli, which also led to an experience of being more connected to nature. Conclusion The WAYA programme was experienced as being of support to childhood and AYA cancer survivors. The programme provided them with skills and tools to be safe in nature. When connected to nature, the participants developed trust and self-confidence, personal growth, relaxation and recovery from stress. Their engagement in outdoor activities continued after completion of the programme, when they returned to everyday life at home.