The intensification of maritime fishing activities, one of the oldest uses of sea by man, has meant that, since already the beginning of the 20th century, marine biological resources, renewable but not inexhaustible, are becoming scarce in some parts of the world. Not surprisingly the efforts of the States to preserve these resources have focused on the regulation of the fishing vessels themselves, gradually subjecting them to a number of restrictions. However, a fishing vessel is not only a means of carrying out a fishing activity; it is, first and foremost, a vessel which, as such, is entitled to the freedoms of navigation international law grants to vessels. Restricting the freedom of navigation of a fishing vessel even when it is not engaged in a fishing activity can contribute to reducing freedom of navigation in general. The Geneva Convention on the Territorial Sea and the Contiguous Zone had already attempted to impose new standards, little covered by customary international law, on the innocent passage of fishing vessels. The 1982 United Nations Convention on the Law of the Sea formally repealed these regulations but mistrust towards fishing vessels is evident in many of its provisions as if the primary goal of any foreign fishing vessel were to infringe national regulations on fishing and conservation of marine resources. The situation becomes more worrying as national regulations acting more or less unilaterally impede the freedom of movement of fishing vessels not only in the territorial sea and the archipelagic waters but also in international straits and in the EEZ. At the same time, the definitions, national and international ones, of what constitutes a fishing vessel are constantly expanding to cover activities of vessels, or even aircraft, which are only indirectly related to what is traditionally understood by fishing.