A high level of swimming can be a protective factor against drowning, however, this relationship has not yet been empirically demonstrated, based on water competence level and aquatic environment. This study designed a drowning risk matrix based on the probabilistic analysis of a questionnaire answered by 3,181 participants. The occurrence of Aquatic Stress/Distress (ASD) was analysed based on 5 skill levels and three aquatic scenarios: a) Pool without waves or currents, b) Lakes, reservoirs, rivers and beaches without waves or currents, c) Rivers, beaches or pools with waves and/or currents. The results were expressed in Odds Ratio (OR). ASD risk exceeded OR of 25 in the most dangerous environment and increased for all scenarios as aquatic competency worsened. Three out of four swimmers have experienced an ASD and this event could have been an incentive to improve their water competence.