Sport and exercise are known to have long-term, positive consequences for the physical and mental health and wellbeing of the individual and society as a whole. In the UK, a quarter of young people experience long-term illness, disability or mental ill-health. However, understanding the impact of surfing on physical and mental health is complex, not least because there are different pathways by which surfing can improve health and wellbeing including: playing, being in nature, socialising, taking risks and identifying as a surfer. The Wave Project is a UK-wide surf therapy charity which provides vulnerable young people aged 8-21 with an opportunity to surf once a week for six weeks. At The Wave Project, clients ‘do’ surfing with the one-to-one assistance of a volunteer overseen by a surf coordinator. After completing The Wave Project clients are invited to become members of a follow-on Surf Club staffed by volunteers or become a Wave Project volunteer themselves. This paper provides an overview of the Wave Project evaluation programme between 2013-2017. During this period there have been three evaluation phases centred around Wave Project delivery: Spring 2013, Summer 2014-Autumn 2015 and Spring-Summer 2017. Each phase has employed a mixture of qualitative and quantitative methods to assess the experience of clients, parents/carers, referrers and Wave Project staff. These methods have included pre- and post-intervention client surveys, focus groups, interviews and log books. The results to-date show that surf therapy can improve the health and wellbeing of vulnerable young people in the UK.