It's quite well known that Spain has a few different types of Police. However, just how many different types are there and what are their roles?
For example, who/what body of police is responsible for foreign nationals when they enter Spanish waters/port/marina in a private yacht which is registered in another European country? What police force is responsible for ports/harbors/marinas in Spain? Who do I initially contact in case of a complaint?
Individual harbours and marinas are usually policed and handled by their own Capitanía Marítima. If you have a complaint to make about the harbour, it is them you should probably contact. The easiest way to find their contact details is to search on google for "Capitanía Marítima XYZ" where XYZ is the name of the harbor/marina you need.
If instead you wish to report a serious issue or a crime, then you should contact the local Servicio Marítimo de la Guardia Civil (SEMAR). If you have a doubt, I would call them and ask for more information. More information about the SEMAR can be found on their official webpage.
Warning: All the links are in Spanish. Use a translate service.
