The paper discusses issues regarding the determination of boundaries of the maritime domain and port area. Despite the well-known disadvantages of the domestic law in this matter, an attempt is made to answer the question of the relevant moment of determining the status of real estate as a maritime domain. This answer should serve as a relevant fact for further action of the competent authorities regarding legal relations related to that real estate. For this purpose, the normative regulation of the determination of boundaries of the mainland component of the maritime domain and port area is analysed, with its application in practice. An overview of the latest case law is given and an analysis is made of the impact of such case law on the existing relations on the maritime domain and port area, especially with regard to ports of special purpose. The final part of the paper analyses the current situation, and a solution to the existing issues is proposed for the purpose of ensuring consistency and legal certainty.