When a marine accident occurs, the lack of experience to face it could lead to social chaos and alarm. Everything gets even worse if the spill involves a Hazardous and Noxious Substance (HNS), because response techniques for this type of substances in marine environments are not well developed. The MARINER project has made a great effort to implement sea response protocols for HNS spills. This video shows some examples of them. The special danger posed by the HNS makes it more essential than ever to train response teams. MARINER project aims to improve planning, preparedness and response to HNS spills in Europe. The coordinated work of trained stakeholders improves protocols and ensures a more efficient response to emergencies. There is no doubt that training exercises are the key to having better protocols and to improve the skills of the different participants involved in the response.