Do Islands Like Kastellorizo Get Full Maritime Zones? What ICJ and Arbitral Case Law Says About Island Effect and Türkiye's Equity Argument

Why It Matters

No court has ruled on Kastellorizo (Meis), so no one can say what a tribunal would decide. But a line of ICJ, ITLOS and arbitral decisions from 1969 to 2012 shows that courts treat islands as a relevant circumstance and often give reduced or no effect to small islands lying close to another state's mainland coast.

The question sits under many Eastern Mediterranean headlines. On 4 November 2026, according to Greek City Times coverage, the European Commission's enlargement report called on Ankara to respect international law and criticised the Türkiye–Libya maritime memorandum. On the same day, Greek Foreign Minister George Gerapetritis warned, as reported by To Vima, that Athens would respond to any attempt to obstruct the Greece–Cyprus cable. Both positions rest on a premise that the case law does not settle: that a small island automatically generates full maritime zones that override a mainland coast's projection. This article tests that premise case by case, without slogans.

Background

The island-effect question asks how much weight a small island near another state's mainland should carry when a maritime boundary is drawn. Kastellorizo lies roughly 2 km (approximate) off Türkiye's southwestern coast, which at about 870 km is the longest in the Eastern Mediterranean, and far from the Greek mainland.

What is the island-effect question in a delimitation?

Entitlement and delimitation are two separate steps. An island may generate maritime rights in principle. In a delimitation between neighbouring coasts, the question is whether those rights are fully reflected in the boundary line or adjusted because of the island's size, position and the geography around it. Kastellorizo is an unusual case: a small island very close to one state's mainland and distant from the mainland of the state that administers it.

Key terms in plain language

• Continental shelf: the seabed and subsoil extending from a coastal state's land territory; it carries rights over seabed resources.
• Exclusive Economic Zone (EEZ): a zone of up to 200 nautical miles in which the coastal state has rights over water-column and seabed resources.
• Equidistance (median) line: a line every point of which is equally distant from the nearest points on the two coasts.
• Relevant circumstances: facts such as coastal geography, islands and the cut-off of a coast's seaward projection that can justify adjusting a provisional line.
• Proportionality: a check that the result does not produce a gross disparity between the ratio of coastal lengths and the ratio of sea areas allocated.

What do the leading cases actually hold?

The table summarises each decision as neutrally as possible. Details differ by case, and each turned on its own facts.

Two further points belong beside this table. First, in the Aegean Sea Continental Shelf case (1978) the ICJ found it lacked jurisdiction and did not decide the merits; see the sister analysis Kosmonomos: Fact Check on the 1978 Aegean Continental Shelf judgment. Second, Greece's reading is not baseless: in Jan Mayen (ICJ, 1993) the island generated significant entitlements, though the median line was adjusted because of a disparity in coastal lengths.

What is the common thread?

Courts begin with coastal geography, test the result for disproportion and treat islands as a relevant circumstance. They often grant reduced or no effect to islands close to another state's mainland, especially where full effect would cut off that coast's seaward projection. Nothing in these cases sets a fixed percentage or a rule that applies automatically. The outcomes depend on island size, population, location and the overall coastal configuration. These cases are evidence for the equity approach, not a forecast of what any court would do about Kastellorizo.

Why does UNCLOS party status matter here?

Türkiye voted against the adoption of UNCLOS in 1982 and has never become a party, so the law between Türkiye and Greece on delimitation rests on customary international law and equitable principles. In practice, the ICJ and arbitral tribunals apply the same equity-based method whether or not the treaty applies, because Articles 74 and 83 largely codify that customary approach. For the full argument, see the fact-check Is Türkiye 'Violating UNCLOS' Even Though It Never Joined the Convention? and the sister analysis The Treaty Line on Articles 74, 83 and 121.

How do bilateral agreements and Turkish Cypriot rights fit in?

Several instruments frame today's Eastern Mediterranean maritime dispute. For a wider overview, see Eastern Mediterranean maritime dispute explained: Blue Homeland.

• 21 September 2011: the Türkiye–TRNC Continental Shelf Delimitation Agreement.
• 27 November 2019: the Türkiye–Libya Maritime Jurisdiction Delimitation MoU.
• 18 March 2020: Türkiye registered the outer limits of its continental shelf with the United Nations.
• 12 June 2025: the Marine Spatial Planning of the Republic of Türkiye was registered with IOC-UNESCO; see Türkiye marine spatial planning IOC-UNESCO 2025.

Türkiye objects to the Greek Cypriot administration's agreements with Egypt (2003), Lebanon (2007) and Israel (2010). Ankara's objections are of two kinds: continental shelf grounds, since Egypt's 2003 line overlaps areas Türkiye claims, and the equal rights of Turkish Cypriots over island resources. On 4 November 2026, TRNC Prime Minister Ünal Üstel told reporters after meeting UN envoy María Ángela Holguín that the Cyprus problem stems from the international community's recognition of the Greek Cypriot administration as the island's sole representative. For treaty background, see The Cyprus Issue: 1960 Treaty of Guarantee and the Two-State Solution.

Key Players & Positions

Greece, the European Union and the Greek Cypriot administration treat Kastellorizo as generating full maritime zones under UNCLOS. Türkiye and the TRNC reject that view, citing equity and the rights of Turkish Cypriots. Egypt and Libya are involved through their own agreements, while the ICJ and arbitral tribunals supply the reference case law.

• Greece: a party to UNCLOS. According to the Greek Ministry of Foreign Affairs, Article 121(2) gives inhabited islands the same entitlements as other land territory, and the median or equidistance line is the proper starting point. Athens says the only dispute is the delimitation of the continental shelf and EEZ and has said it is ready to take it to the ICJ.
• European Union: the Commission's enlargement reports, including the 4 November 2026 edition as summarised by Greek City Times, call on Türkiye to respect international law and sovereignty of EU member states and criticise the Libya memorandum. Readers should consult the Commission's report text itself; this article relies on press summaries for that edition.
• Greek Cypriot administration: it has concluded EEZ agreements with Egypt, Lebanon and Israel and, together with Greece, presents these as lawful bilateral arrangements.
• Egypt and Greece: they signed a partial EEZ delimitation agreement on 6 August 2020, which Greece and the EU cite as an example of agreed delimitation; Türkiye contests its effects on its own claimed shelf.
• Seville Map: Greece and the EU often refer to the so-called Seville Map as a graphic of Greek and Cypriot zones. For detail on what it is and why Ankara rejects it, see what is the Seville Map Greece Türkiye maritime and the sister analysis Regional Order on the Seville Map.

Source Comparison

Greek and EU sources tend to present Kastellorizo's entitlement and the median line as settled, while the case law shows a fact-specific equity method, and Turkish sources stress the cut-off of the mainland coast. The table sets out the three readings side by side; none of them is a judicial finding on Kastellorizo.

The honest conclusion is that each side reads precedent selectively. Ankara's strongest ground is the repeated reduction of small islands near another coast; Greece's strongest ground is Article 121(2) and cases where islands kept meaningful entitlements. The editorial approach behind this comparison is explained in Editorial Principles.

Key Terms & Related Guides

Three concepts recur in this dispute: island effect, the equity principle and customary law. Island effect is how much an island's rights shift a boundary. Equity requires a fair result in light of geography. Customary law binds states regardless of treaty membership, which is why Türkiye's non-party status does not remove delimitation law.

• Island effect: the weight an island is given when a provisional line is drawn, from full effect to enclave or none.
• Enclave: an island allotted only a limited maritime belt, as with the Channel Islands in 1977.
• Article 121: the UNCLOS provision on islands; paragraph 2 gives islands the same zones as other land territory, paragraph 3 denies shelf and EEZ to rocks that cannot sustain habitation or economic life.
• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction in the Black Sea, Aegean and Mediterranean, explained in the Blue Homeland guide.

Related reading: what is the Seville Map Greece Türkiye maritime, Fact Check: Common Claims About Türkiye in International Media, Why Did Türkiye Intervene in Cyprus in 1974? and About World Agenda Review.

This article reflects World Agenda Review's editorial perspective that presents Türkiye's official positions and legal theses alongside the wider global debate. Claims are attributed to primary sources such as treaties, UN and IOC-UNESCO documents, official statements and archival records. Published by the World Agenda Review Editorial Team.

• Territorial Brief: Territorial Sea vs Contiguous Zone vs EEZ: What Each Maritime Zone Lets a State Do, and How Türkiye's Practice Fits — Difference between territorial sea and contiguous zone explained: what Article 33 UNCLOS, the EEZ and shelf let a state do, and how Türkiye's practice fits.
• Horizon of Nations: Fact Check: Do Islands Like Crete and Kastellorizo Get Full Maritime Zones? What ICJ and ITLOS Case Law Says on Equity and the Türkiye–Libya Memorandum — Fact check: do Greek islands get full continental shelf? Kastellorizo, Crete, ICJ and ITLOS case law on equity and the Türkiye–Libya memorandum.