Physical activity has been shown to have many benefits, including reducing cancer-related fatigue (CRF) and improving psychological and physical recovery from breast cancer. Some authors have shown the benefits of aquatic practice, while others have detailed the benefits of group and supervised practice. We hypothesize that an innovative sports coaching proposal could allow a significant adherence of patients and contribute to their health improvement. The main objective is to study the feasibility of an adapted water polo programme (aqua polo) for women after breast cancer. Secondarily we will analyse the effect of such a practice on patients' recovery and study the relationship between coaches and participants. The use of mixed methods will allow us to question the underlying processes precisely. This is a prospective, non-randomized, monocentric study with a sample of 24 breast cancer patients after treatment. The intervention is a 20 week programme (1 session per week) of aqua polo in a swim club facility, supervised by professional water-polo coaches. The variables measured are patient participation, quality of life (QLQ BR23), CRF (R–PFS) and post-traumatic growth (PTG-I) as well as different variables to observe physical capacity (strength with dynamometer, step-test and arm amplitude). The quality of the coach-patient relationship will be evaluated (CART-Q) to explore its dynamics. Participatory observations and interviews will be carried out to report on the interactions between the coach and the participants during the sessions. Registration number and name of trial registryNo. EudraCT or ID-RCB: 2019-A03003-54 and NCT: NCT04235946