Maritime Boundary

A maritime boundary is the line dividing the maritime zones of two states with adjacent or opposite coasts. For the territorial sea, UNCLOS Article 15 sets the median line as the default absent agreement, historic title, or special circumstances. For the EEZ and continental shelf, Articles 74 and 83 require delimitation by agreement to achieve an equitable solution; where states cannot agree, they resort to Part XV dispute settlement. Courts and tribunals apply the three-stage equidistance-relevant-circumstances-proportionality method developed in Romania v. Ukraine (2009) and applied in Bangladesh/Myanmar (ITLOS, 2012) and Nicaragua v. Colombia (ICJ, 2012). A single maritime boundary may delimit several zones at once.