In April 2025, Greece announced its first marine spatial planning (MSP), accompanied by an official map which divides the Ionian and the Aegean Seas into four different spatial units (See here for the official announcement in Greek – The map is further provided and explained below). While MSP in Greece had been under discussion for years, prompted by Greece’s obligations under EU Directive 2014/89/EU, this announcement marks the first time Greece has officially mapped the entirety of its maritime claims. While MSP is primarily a domestic tool for environmental coordination and resource management, its adoption in a legally contested maritime space necessarily raises issues of international law and the law of the sea.
This post explores the legal relevance of Greece’s MSP from the perspective of international law. First, it introduces the concept of MSP and the context of its publication. Second, it analyses the evidentiary function of maps in boundary disputes, focusing on how such instruments can contribute to the stabilisation of legal claims. Finally, it considers the role of MSP within the framework of UNCLOS obligations in undelimited maritime zones. This post suggests that, irrespective of broader geopolitical narratives, such regulatory acts may support (rather than hinder) the eventual process of maritime delimitation by clarifying States’ positions and fostering dialogue.