One of the fundamental concepts of the Convention on the Law of the Sea is that of the baselines, where from the breadth of the maritime zones is measured. Baselines, delimiting the land and internal waters from the sea, can be any combination of normal, straight, archipelagic or bay-closing lines. The determination of the coastline indentations at which the coastal State is entitled to draw bay-closing lines has been a complicated and time-consuming task. Existing GIS environments carry out the process semi-automatically with the user undertaking the location of the candidate indentation and the software validating the length and semi-circle criteria stipulated by the Convention. This process has the inherent weakness that indentations meeting both criteria may remain undetected. This paper presents, implements and evaluates a methodology for the determination of all indentations along the coastline that can be closed with bay-closing lines without the intervention of the user. The proposed methodology addresses the issue of juridical bays in its entirety, including the existence or absence of headlands, the presence of islands in the mouth of the bay, as well as the maximization of the area of the bay, something that currently available solutions are lacking in.