Within the ports, as part of the customs areas, defined as the locals in which it operates a customs service, as well as the areas on which the customs exercise supervision and control by means of its organs or by direct Guard finance, the body carries out supervision and assistance in customs operations to ensure the respect of the rules established to guarantee the collection of rights and to ensure compliance with the regulations concerning the movement and storage of goods, in order to prevent them from being performed subtraction, confusion, replacements or operations not permitted, as well as self-control activities for the detection of outgoing correspondence of the goods with the relevant customs documents and the visit of the goods in the event of a serious presumption of irregularity.