Objective: to create a legal mechanism for unification of the legal norms regulating the commercial operation of maritime transport.Methods: historical-legal, formal-logical, systemic, comparative-legal, statistical methods.Results: the relevance of the topic is due to the importance of the development of specific legal relations in maritime transport and the need to understand the inseparability of coastal infrastructure and transportation-technological port complexes for the commercial shipping development. The paper deals with the problem of limiting the entry of commercial ships to sea ports and the need to find an optimal mechanism for documenting the arrival of merchant ships in foreign ports. The authors set the task to analyze the historical background of the principle of free access to seaports and the development of seaports legal regime. The study was based on international-legal and national-legal norms of various states, as well as judicial practice. The authors studied the work of International Law Institute for the unification of international norms regulating the regime of vessels in foreign ports, considered the provisions of the Convention and Statute on the international regime of maritime ports, and the rules of national law of foreign states. It is concluded that the established custom for foreign vessels to entry sea trade ports is by recognizing them to be open ports. Scientific novelty: it is connected not only with the justification of the right of the state as a sovereign to establish general rules of navigation and mooring of ships in seaports and approaches to them, but also with the analysis of the current situation complicated by the sanctions policy of some states. In this article, the authors came to the conclusion that the optimal mechanism for improving and optimizing foreign economic relations in the field of maritime law can be the unification of legal norms governing the commercial operation of maritime transport, in particular when registering the arrival of merchant ships in seaports.Practical significance: the main provisions and conclusions of the article can be used in scientific, pedagogical and law enforcement activities when studying the issues related to commercial shipping.