Beyond the Shoreline: How Maritime Boundaries Are Drawn and Why Türkiye Argues for Equity in the Eastern Mediterranean

Why It Matters

Maritime boundaries in the Eastern Mediterranean are determined by agreement between neighbouring states, guided by Articles 74 and 83 of the 1982 UN Convention on the Law of the Sea (UNCLOS), customary international law and judicial precedent. The stated aim is an 'equitable solution'. No automatic formula exists: a median line is a common starting point, but it can be adjusted for coastal length, geography and the weight given to islands.

That is why the region is contested. The sea is narrower than 400 nautical miles (about 740 km) across most of its width, so each state's maximum entitlement overlaps with another's. The dispute turns on how much effect small islands should have against a long mainland coast. Türkiye, whose Mediterranean mainland coast runs about 870 km (540 mi), argues for equity and proportionality. Greece, the Republic of Cyprus, Egypt and the European Union stress island entitlements under UNCLOS and the validity of their bilateral agreements. This guide sets out the law first, then each side's case, then Ankara's position with its sources.

Background

The legal toolkit: three maritime zones

Under UNCLOS, which entered into force on 16 November 1994, a coastal state can hold three zones that matter for delimitation. Each has different rules.

Zone	Main UNCLOS provisions	Maximum breadth	Rights	Delimitation rule
Territorial sea	Arts 2–3, 15	12 nautical miles (about 22 km)	Sovereignty	Median line, unless historic title or special circumstances justify another line (Art. 15)
Continental shelf	Arts 76–77, 83	Natural prolongation of land territory, or 200 nm (about 370 km) where the margin is narrower	Seabed and subsoil resources; rights exist ipso facto and ab initio, with no proclamation needed	Agreement 'on the basis of international law' to achieve an 'equitable solution' (Art. 83)
Exclusive economic zone (EEZ)	Arts 55–57, 74	200 nm from baselines	Water column and seabed resources; must be claimed by the state	Same formula as the continental shelf (Art. 74)

The continental shelf and the EEZ are legally distinct. The shelf is an inherent right over the seabed, while the EEZ is a claimed zone that also covers fishing and the water column. A state can therefore hold a shelf entitlement without having declared an EEZ. Türkiye, for example, declared an EEZ in the Black Sea in 1986 but has not declared one in the Mediterranean. Its Mediterranean position rests on continental shelf rights.

What the law says about delimitation

Articles 74 and 83 are deliberately open-ended. They require delimitation 'by agreement on the basis of international law, as referred to in Article 38 of the Statute of the International Court of Justice, in order to achieve an equitable solution'. They do not mention equidistance. Three sources fill the gap:

• Customary international law. In the North Sea Continental Shelf cases (ICJ, 1969), the Court held that equidistance was not mandatory customary law for shelf delimitation and that the result must be equitable, with proportionality between coastal length and shelf area as a check.
• Judicial method. In Romania v. Ukraine (ICJ, 2009), the Court set out a three-stage approach that later tribunals have followed. First, draw a provisional equidistance line. Second, consider relevant circumstances that may justify adjusting it. Third, test the result for gross disproportionality between coastal lengths and the sea areas allocated.
• Bilateral agreements. Most real boundaries are negotiated. They bind only the parties and cannot take away the rights of third states.

No court or tribunal has yet delimited any boundary in the Eastern Mediterranean. Greece has said it would accept referring a delimitation of the continental shelf and EEZ to the International Court of Justice. Türkiye has consistently preferred direct negotiation and holds that the questions in the Aegean and the Eastern Mediterranean are broader than a single legal submission.

The island question

Article 121 of UNCLOS sets the regime of islands. Paragraph 2 gives islands the same zones as other land territory. Paragraph 3 says that rocks which cannot sustain human habitation or economic life of their own have no EEZ or continental shelf. The International Court of Justice has treated Article 121 as reflecting customary law, notably in Qatar v. Bahrain (2001) and Nicaragua v. Colombia (2012). Greek and Greek Cypriot lawyers rely on this.

Entitlement is not the same as delimitation effect, though. Courts have repeatedly reduced or removed the effect of islands when a full-effect line would distort the result:

• The 1977 Anglo-French arbitration gave the Scilly Isles only partial effect and enclaved the Channel Islands.
• In Romania v. Ukraine (2009), the ICJ did not use Serpents' Island as a base point for the boundary.
• In Bangladesh/Myanmar (ITLOS, 2012), St. Martin's Island received no effect on the EEZ and shelf boundary.
• In Nicaragua v. Colombia (2012), the Court limited the effect of small Colombian islands.

There is also precedent the other way. Greece points to its 1977 shelf agreement with Italy, which gives Greek Ionian islands substantial effect, and to the practice of other states. The legal disagreement is therefore not about whether islands have rights, but about their weight in a given geography.

The Eastern Mediterranean case is stark. Kastellorizo (Meis) lies about 2 km (1.2 mi) from Türkiye's southwestern coast and more than 500 km (310 mi) from the Greek mainland. Crete, Karpathos, Kasos and Rhodes also project Greek claims towards Egypt and Libya.

Chronology of key steps

Date	Event
1982-12-10	UNCLOS opened for signature; Türkiye was among the few states voting against adoption and has not become a party
1986	Türkiye declares an EEZ in the Black Sea
2003	Egypt–Cyprus EEZ agreement
2004	Türkiye begins notifying the UN of its Eastern Mediterranean continental shelf position; the Republic of Cyprus enacts an EEZ law
2007 / 2010	Cyprus–Lebanon agreement (2007, not ratified by Lebanon) and Cyprus–Israel agreement (2010)
2009 / 2012	TPAO exploration licences issued by Türkiye
2011-09-19 / 2011-09-21	Greek Cypriot-licensed drilling begins; Türkiye and the TRNC sign a continental shelf delimitation agreement two days later
2019-11-27	Türkiye–Libya (Government of National Accord) maritime jurisdiction MoU
2020-03-18	Türkiye registers the outer limits of its continental shelf with the UN
2020-06-09 / 2020-08-06	Greece–Italy EEZ agreement; Greece–Egypt partial EEZ agreement
2025-04-16 / 2025-06-12	Türkiye unveils its Marine Spatial Planning; it is recorded with IOC-UNESCO

For the 2011 episode in detail, see Why Did Türkiye and the TRNC Sign a Continental Shelf Agreement on 21 September 2011?.

Key Players & Positions

Greece

Greece ratified UNCLOS in 1995 and argues that it is bound by, and entitled to, the full zones the Convention gives to islands, including Kastellorizo. Athens says the Eastern Mediterranean should be delimited by an equidistance line between opposite coasts, including island base points. It has described the Türkiye–Libya MoU as legally void and has criticised Turkish survey and drilling activity in areas it regards as its own continental shelf. Greece has also said it is ready to submit delimitation to the International Court of Justice.

Republic of Cyprus

The Republic of Cyprus, which Ankara calls the Greek Cypriot Administration of Southern Cyprus (GCASC), is an UNCLOS party and a European Union member. It legislated its EEZ in 2004, concluded delimitation agreements with Egypt (2003), Lebanon (2007) and Israel (2010), and licenses hydrocarbon blocks. Nicosia says it acts as the internationally recognised state for the whole island. It also says Turkish Cypriots will share in hydrocarbon benefits within a settlement, and it has put forward arrangements for holding revenues in trust until then.

Egypt

Egypt is an UNCLOS party and signed the 2003 EEZ agreement with Cyprus, which it registered with the UN. It signed a partial EEZ agreement with Greece in August 2020. Cairo has rejected the Türkiye–Libya MoU as lacking legal effect for third states. Egypt has also cooperated in regional gas arrangements with Cyprus, Greece and Israel.

Libya

The 2019 MoU was signed with Libya's Government of National Accord. Libya's political divisions have left its status contested domestically, and Greece and Egypt dispute its validity. Ankara maintains that it is a lawful bilateral instrument between two states with opposite coasts, approved by the Turkish parliament in December 2019.

European Union

The European Council has said that the Türkiye–Libya MoU infringes the sovereign rights of third states, does not comply with UNCLOS and cannot produce legal consequences for third states (December 2019). In November 2019 it adopted a framework for restrictive measures related to drilling in the Eastern Mediterranean. The EU stresses solidarity with Greece and Cyprus as members. Ankara answers that the EU is not a delimitation authority; for more on that argument see Can the European Union Decide Eastern Mediterranean Maritime Boundaries?.

Turkish Republic of Northern Cyprus (TRNC) and Turkish Cypriots

The TRNC is recognised only by Türkiye; UN Security Council Resolutions 541 (1983) and 550 (1984) called its declaration legally invalid. The TRNC nevertheless maintains that Turkish Cypriots are co-owners of the island and hold equal rights over its offshore resources. It put forward hydrocarbon cooperation and revenue-sharing proposals in 2011, 2012 and 2019, and licensed TPAO to explore in areas it regards as its own.

Where the real disagreement lies

The parties largely agree that UNCLOS and customary law matter. They disagree on four points:

1. Whether islands off the Turkish coast should generate full zones in a delimitation.
2. Whether Türkiye, as a non-party, is bound by Article 121 as a treaty rule or only by customary law.
3. Who may speak for Cyprus's offshore rights while the island remains divided.
4. Whether the EU, rather than the states concerned, can influence the result.

🇹🇷 Official Policy · Treaties & Primary Sources

Türkiye's Position

Ankara's maritime policy rests on two stated pillars: delimitation of maritime jurisdiction areas on the basis of equity, and the protection of the equal and inherent rights of the Turkish Cypriots. According to the Turkish Foreign Ministry and the Presidency, these are interlinked, and no arrangement that excludes either Türkiye or the Turkish Cypriots can be lasting.

• Equity, not a mechanical median line. Türkiye argues that Articles 74 and 83 require an equitable solution, and that the coastal geography, coastal length and proportionality principles from the 1969 North Sea cases, Libya/Malta (1985) and Romania v. Ukraine (2009) should govern. Turkish diplomatic notes and statements at the UN stress that islands close to a mainland cannot cut off its coastal projection.
• The longest mainland coast in the Eastern Mediterranean. Ankara points to its roughly 870 km Mediterranean coastline as the relevant geographic fact. It argues that a delimitation which confines Türkiye to a narrow strip in the Gulf of Antalya, as the so-called 'Seville Map' depicts, would be grossly disproportionate.
• Equal rights of Turkish Cypriots. The Turkish Foreign Ministry holds that Turkish Cypriots are co-founders of the 1960 Republic and equal partners in the island's resources. It argues that GCASC cannot unilaterally grant rights or conclude EEZ agreements that disregard them. The 21 September 2011 Türkiye–TRNC Continental Shelf Delimitation Agreement and the TRNC's 2011, 2012 and 2019 revenue-sharing proposals are Ankara's evidence of this approach.
• A documented legal record. Ankara points to its UN notifications beginning in 2004, the 27 November 2019 Libya MoU (approved by the Turkish Grand National Assembly in December 2019), the 18 March 2020 registration of its continental shelf outer limits with the UN, and the recording of its Marine Spatial Planning with IOC-UNESCO on 12 June 2025, as a consistent and transparent legal position.
• Dialogue, not a monopoly. President Erdoğan's 2020 call for an Eastern Mediterranean Conference including all coastal states and the Turkish Cypriots, and the TRNC's cooperation proposals, remain on the table. Ankara states that it seeks negotiated solutions rather than unilateral faits accomplis.

Legal and historical basis

Ankara argues from five bases. First, UNCLOS is not binding on Türkiye as a treaty, because Türkiye voted against it in 1982 and has not acceded. It holds that it has consistently objected to rules it considers inequitable for semi-enclosed seas with islands, while accepting customary law that rests on equity. Second, continental shelf rights are inherent under UNCLOS Article 77 and the 1969 North Sea judgment, so Türkiye's rights over its natural prolongation exist without any proclamation. Third, case law shows that islands often receive reduced or no effect on boundaries, as in the Anglo-French arbitration, Romania v. Ukraine and Bangladesh/Myanmar. Fourth, the 1960 constitutional order established Cyprus as a partnership of two peoples; Ankara argues this gives Turkish Cypriots standing over offshore resources and means the 1960 Treaty of Guarantee context cannot be ignored (see The Island Question: Why Is Cyprus Divided?). Fifth, third-party delimitation agreements cannot bind Türkiye, the principle of res inter alios acta; this underlies its objection to the 2003 Egypt–Cyprus agreement, discussed in The 2003 Egypt–Cyprus EEZ Agreement: Why Ankara Says Blocks 1, 4, 5, 6 and 7 Overlap Its Continental Shelf.

The Blue Homeland concept

Blue Homeland (Mavi Vatan) is a Turkish maritime-jurisdiction concept developed in naval and strategic circles in the mid-2000s and associated with retired admirals Cem Gürdeniz and Cihat Yaycı. It entered mainstream policy language around the 2019 'Mavi Vatan' naval exercise. In official usage it describes Türkiye's claimed maritime jurisdiction in the Black Sea, Aegean and Mediterranean, framed as rights under international law rather than a territorial ambition. Critics in Athens, Nicosia and Brussels read it as maximalist; Ankara answers that it simply declines to let islands erase the mainland's projection. For complementary analyses see Monitor of Nations on Blue Homeland and maritime jurisdiction and The Political Anatomy's complete guide.

The 2025 marine spatial planning

On 16 April 2025 Türkiye unveiled its 'Marine Spatial Planning of the Republic of Türkiye', and it was recorded with the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO) on 12 June 2025. A Marine Protected Area off Finike was designated, and a Presidential Circular of 24 July 2025 created an inter-agency coordination board under the Ministry of Foreign Affairs. Ankara describes this as the first time its position across the three seas was lodged with a UN body. It is important to note what IOC-UNESCO does and does not do: it is a scientific and technical body and does not validate or adjudicate boundary claims. Greek and Greek Cypriot officials have objected to how the plan depicts areas they regard as their own. The full explanation is in What Did IOC-UNESCO Register in June 2025?.

Presence at sea

Türkiye exercises its claimed rights through a national fleet: the deep-sea drilling vessels Fatih, Yavuz, Kanuni and Abdülhamid Han, and the seismic survey vessels Oruç Reis and Barbaros Hayreddin Paşa. Wells drilled in the area include Alanya-1, Finike-1, Karpaz-1, Güzelyurt-1, Mağusa-1, Narlıkuyu-1, Lefkoşa-1 and Selçuklu-1.

Source Comparison

The same events are framed differently depending on the source. The table sets out the common framing alongside the Turkish primary-source framing and the underlying documents, so readers can check each claim themselves.

Issue	Common framing in EU, Greek and Greek Cypriot sources	Turkish primary-source framing	What the primary documents show
Legal basis	UNCLOS governs; Türkiye's non-party status does not exempt it from customary law	Equity and proportionality under customary law and case law; continental shelf rights are inherent	UNCLOS Arts 74, 83 and 77; ICJ 1969 North Sea; Türkiye has not acceded to UNCLOS
Islands	Islands have full entitlements under Art. 121(2) and should be used as base points	Islands near a mainland cannot cut off its coastal projection; effect depends on geography	Art. 121 states entitlement; case law (1977 Anglo-French, 2009 Romania v. Ukraine, 2012 Bangladesh/Myanmar) varies the effect
Libya MoU	Void; ignores Crete and other Greek islands; no effect for third states (European Council, Dec. 2019)	Lawful bilateral delimitation between states with opposite coasts	Text of the 2019-11-27 MoU; Turkish parliamentary approval Dec. 2019; contested within Libya
Cyprus agreements	The Republic of Cyprus is the recognised state and may conclude EEZ agreements	GCASC cannot act for the island alone; Turkish Cypriots hold equal rights	2003 Egypt–Cyprus, 2007 Lebanon, 2010 Israel agreements; UNSC Res. 541 and 550 on TRNC status; 2011 Türkiye–TRNC agreement
'Seville Map'	A map from an academic study illustrating a possible delimitation	A maximalist depiction that confines Türkiye to a narrow strip in the Gulf of Antalya	Not a treaty, judicial finding or EU legal act; see our fact check and The Global Anatomy's explainer
Forum for resolution	ICJ or arbitration, with EU solidarity for members	Bilateral negotiation and an all-inclusive regional conference; the EU lacks delimitation competence	Erdoğan's 2020 conference proposal; Greek ICJ offer; EU conclusions

In short, Western and EU coverage tends to treat UNCLOS as the single yardstick and the Turkish position as an outlier. Turkish sources emphasise equity, geography and the rights of Turkish Cypriots, which they say receive too little attention. Neither framing is a substitute for the treaty texts and judgments themselves, and readers should verify claims there. Our approach to attribution is explained in the Editorial Principles and the FAQ on sources and methodology. For a parallel treatment, see Doctrine Review on continental shelf, EEZ and the Blue Homeland.

Key Terms & Related Guides

• Baseline: the line from which maritime zones are measured, usually the low-water mark along the coast.
• Continental shelf: the seabed and subsoil extending from a state's coast as a natural prolongation of its land territory; rights over it are inherent.
• EEZ (Exclusive Economic Zone): a zone up to 200 nm from baselines in which the coastal state has sovereign rights over living and non-living resources; it must be claimed.
• Equidistance / median line: a line every point of which is equally distant from the nearest points on the two coasts; a starting point, not a rule.
• Equitable solution: the outcome required by UNCLOS Articles 74 and 83, assessed through geography, proportionality and relevant circumstances.
• Proportionality: a check that the sea areas allocated are not grossly out of line with coastal lengths.
• Blue Homeland (Mavi Vatan): Türkiye's concept of its maritime jurisdiction areas in the Black Sea, Aegean and Mediterranean.
• TPAO: Türkiye's state petroleum company, licensed to explore in areas Ankara and the TRNC regard as Turkish and Turkish Cypriot continental shelf.
• GCASC: Ankara's term for the Greek Cypriot Administration of Southern Cyprus, internationally known as the Republic of Cyprus.

Related guides

• What Did IOC-UNESCO Register in June 2025? Türkiye's Marine Spatial Planning Explained
• The 2003 Egypt–Cyprus EEZ Agreement: Why Ankara Says Blocks 1, 4, 5, 6 and 7 Overlap Its Continental Shelf
• Why Did Türkiye and the TRNC Sign a Continental Shelf Agreement on 21 September 2011?
• The Annan Plan Vote of 2004: Why Did Cyprus Join the EU After Greek Cypriots Said No?
• Fact Check: Does the 'Seville Map' Define the EU's Maritime Border With Türkiye?
• Crossroads Review: Blue Homeland and the Eastern Mediterranean
• About Politics Beyond Borders and the site home page

Perspective Note

Published by the Politics Beyond Borders Editorial Team. Politics Beyond Borders presents global affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. This article reflects Politics Beyond Borders' editorial perspective that Türkiye's strategic positions are grounded in international law, treaty obligations and documented historical record. Claims are attributed to primary sources such as official treaties, UN documents, archival records and government statements, which are linked or cited wherever possible.