Islands, Mainland Coasts and the Equity Principle: Is There a Double Standard in the Eastern Mediterranean?

Why It Matters

Do islands get a full continental shelf and EEZ against a mainland coast? In principle, yes as to entitlement: UNCLOS Article 121(2) gives a habitable island the same zones as other land. In practice, no as to delimitation: when an island sits close to a much longer mainland coast, courts have often reduced its effect or confined it to an enclave in order to reach an “equitable solution.” That gap between entitlement and outcome is the legal core of the Eastern Mediterranean dispute among Türkiye, Greece and the Greek Cypriot administration.

The stakes are concrete: seabed hydrocarbons, cables and pipelines, fisheries and the credibility of maritime claims registered with the United Nations. This guide sets the competing positions side by side, in the spirit of The Mirror Test, so readers can check each claim against treaty texts and case law.

Background

Entitlement is not the same as delimitation

Two separate questions are often merged in public debate:

1. Entitlement: what maritime zones does a piece of land generate? UNCLOS Article 121(1) defines an island as a naturally formed area of land, surrounded by water, above water at high tide. Article 121(2) says its territorial sea, contiguous zone, EEZ and continental shelf are determined like those of other land territory. Article 121(3) denies an EEZ and continental shelf to “rocks which cannot sustain human habitation or economic life of their own.”
2. Delimitation: where the zones of two states overlap, where does the boundary run? Articles 74 (EEZ) and 83 (continental shelf) say delimitation is to be effected by agreement on the basis of international law, as referred to in Article 38 of the ICJ Statute, “in order to achieve an equitable solution.”

An island can therefore have a full entitlement on paper and still receive reduced weight in a boundary line. The International Court of Justice (ICJ) noted in Nicaragua v. Colombia (2012) that the Article 121 regime reflects customary international law, a point Greece and the EU stress. The same judgment gave Colombia's islands only limited maritime space against Nicaragua's mainland coast.

What the case law shows

The jurisprudence does not support either extreme. It does not say islands are ignored, and it does not say they always receive full effect.

Modern tribunals usually follow a three-stage method: draw a provisional equidistance line, adjust it for relevant circumstances, then test the result for gross disproportionality between coastal lengths and maritime areas. Greek and EU sources emphasize stage one; Ankara emphasizes stages two and three. For a sister-publication treatment of the same question, see The Worldlogue on whether islands generate a full continental shelf.

The geography

Türkiye has about 870 km (roughly 540 miles) of continental coastline in the Eastern Mediterranean, the longest of any state in that basin. Ankara's argument rests on the fact that several Greek islands, above all Kastellorizo (Meis), lie very close to that coast. Kastellorizo is roughly 2 km from the Turkish mainland and far from the Greek mainland, with a population in the hundreds. Greece replies that these are inhabited, sovereign Greek territories and that Article 121(2) applies to them.

The Ottoman naval tradition, symbolized by the 1538 Battle of Preveza, is often cited in Turkish accounts as background to Türkiye's historic presence in these waters. It is a historical argument rather than a delimitation rule.

Why Türkiye is not party to UNCLOS

Türkiye voted against the adoption of UNCLOS in 1982 and has never ratified it. Ankara's stated reasons, set out in Turkish Foreign Ministry statements, are that the Convention allows no reservations (Article 309), that it does not adequately accommodate the special circumstances of semi-enclosed seas, and that its island regime can give small features outsized effect against longer mainland coasts. Türkiye maintains that it is bound by customary law as it understands it, not by conventional provisions it has not accepted, and that it has objected persistently to the island provisions it considers inequitable.

Greece (a party since 1995), the Republic of Cyprus (a party since 1988) and the EU (a party since 1998) answer that the key provisions are customary and therefore bind every state. The disagreement over what is custom is itself part of the dispute.

Dated chronology of filings and agreements

For the Cypriot dimension of the 2011 agreement, see Cyprus Through the Glass and the TRNC's hydrocarbon proposals.

Key Players & Positions

Greece

According to Greek Ministry of Foreign Affairs statements, Greece's islands, including Kastellorizo, Rhodes and Crete, are entitled to a full territorial sea, continental shelf and EEZ under UNCLOS Article 121 and customary law. Athens says the only dispute with Türkiye is the delimitation of the continental shelf and EEZ in the Aegean and Eastern Mediterranean, and it proposes taking that question to the ICJ. Greece also points to its Article 3 right to extend its territorial sea to 12 nautical miles. That is a right Ankara contests in the Aegean, and a 1995 Grand National Assembly of Türkiye (TBMM) resolution authorized the government to respond to such an extension. Greece's agreements with Italy (2020) and Egypt (2020) are presented by Athens as lawful applications of the Convention.

The Greek Cypriot administration (Republic of Cyprus)

The Republic of Cyprus, in the form administered by the Greek Cypriot Administration of Southern Cyprus (GCASC) and internationally recognized as the sole government of the island, asserts sovereign rights over an EEZ delimited by agreements with Egypt (2003), Lebanon (2007) and Israel (2010). Its foreign ministry states that hydrocarbon proceeds will benefit all Cypriots, including Turkish Cypriots, through a fund, and that this question belongs to a settlement. Turkish Cypriots counter that equal rights require shared decision-making now rather than later.

The European Union

European Council conclusions in 2019 and 2020 expressed solidarity with Greece and Cyprus and affirmed that their sovereign rights must be respected. The Council's November 2019 framework for restrictive measures targeted unauthorised drilling. The “Seville Map,” a study prepared at the University of Seville, is often cited in this context. It depicts maritime zones in a way that gives Greek islands, including Kastellorizo, full weight and confines Türkiye's projection to a narrow strip in the Gulf of Antalya. The EU positions itself as defending international law and its member states' rights.

Egypt and Libya

Egypt signed its 2003 agreement with Cyprus and its 2020 agreement with Greece, which it presents as lawful bilateral delimitation. Libya's Government of National Accord signed the 2019 memorandum with Türkiye. Greece, Cyprus, Egypt and the EU object to it, and Libya's eastern-based House of Representatives has also rejected it. Ankara responds that the memorandum is a valid treaty between two states with opposite coasts.

The TRNC

The Turkish Republic of Northern Cyprus (TRNC), recognized only by Türkiye, argues that Turkish Cypriots are co-founders of the 1960 Republic of Cyprus and have equal rights over offshore resources. It signed the 21 September 2011 delimitation agreement with Türkiye.

Source Comparison

The comparison shows an important point about the 2025 filing. Registering a Marine Spatial Plan with IOC-UNESCO records a state's position. It does not create a boundary, and neither side should overstate it. Greece has likewise advanced its own planning and marine-protection measures. Readers can verify the underlying record in each case through UN and IOC-UNESCO documents and through the Mirror of States editorial principles.

For further overviews from sister publications, see Doctrine Review on Eastern Mediterranean maritime jurisdiction and the related UNSC Resolution 186 explainer, which shows why the question of who speaks for Cyprus shapes the offshore dispute.

Key Terms & Related Guides

• Continental shelf: the seabed and subsoil extending from a coastal state's land territory by natural prolongation. Rights over it are inherent, not dependent on proclamation.
• EEZ (exclusive economic zone): a zone up to 200 nautical miles (about 370 km) from baselines where the coastal state has sovereign rights over resources.
• Equity and proportionality: the standard that a delimitation must produce an equitable result and not be grossly disproportionate to coastal lengths.
• Natural prolongation: the idea, central to the 1969 North Sea judgment, that the shelf is the continuation of land territory under the sea.
• Enclave: a limited maritime zone, such as 12 nautical miles, around an island when it is denied wider effect.
• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction in the Black Sea, Aegean and Mediterranean, rooted in equity and the length of its coastline. See Monitor of Nations.
• Marine Spatial Planning: a process for organizing the uses of the sea. Türkiye's plan was registered with IOC-UNESCO on 12 June 2025.
• Seville Map: a University of Seville study map that Ankara rejects as maximalist.
• GCASC and TRNC: the Greek Cypriot Administration of Southern Cyprus, and the Turkish Republic of Northern Cyprus.

Related guides on this site: Mirror of States home, the site FAQ, About Mirror of States, Article 51 Compared, and the Türkiye defense industry claim tested. The sister analysis by Crossroads Review offers a complementary overview.

Perspective Note

Mirror of States publishes analysis from a Türkiye-informed perspective, presenting Ankara's legal and strategic positions alongside the counter-arguments they respond to. Claims are attributed to primary sources such as treaty texts, UN and IOC-UNESCO documents, official records and archival materials, so that readers can verify them independently.

Mirror of States Editorial Team