Fact Check: Does the 'Seville Map' Set Maritime Boundaries in the Eastern Mediterranean?

Why It Matters

The Seville Map does not set any maritime boundary in the Eastern Mediterranean. It is a cartographic output of a study. It is not a delimitation treaty, a court award or an arbitral decision, and no state or international body has adopted it as a binding line. The claim matters because the map is often described in headlines and social media as though it fixed the zones of Greece and the Greek Cypriot administration of Southern Cyprus (GCASC) and confined Türkiye to a narrow strip in the Gulf of Antalya.

This fact check states the claim and its origin, then compares it with the legal record: the law of the sea, the decided cases, the EU's own competences and the documents each side has filed. It also sets out how Greece, the GCASC and the EU describe the map, and where Ankara's objections come from. For the wider legal landscape, see our guide to Eastern Mediterranean Corridors: Shipping Lanes, Pipelines, Cables and the Jurisdiction Beneath Them.

Claim vs. Fact Analysis

Claim 1: 'The Seville Map sets the maritime zones of Greece and Cyprus'

The claim and its origin. The 'Seville Map' takes its name from a study prepared by researchers at the University of Seville, Spain, on how maritime zones might be delimited in the Eastern Mediterranean. It circulated in Greek, Greek Cypriot and Turkish media from around 2018–2020 and is widely described as 'EU-linked' because it was discussed in the context of EU debates and cited in arguments about 'Union solidarity' with Athens and Nicosia. In its most common form, the claim says the map fixes Greek and Greek Cypriot zones and leaves Türkiye only a small area near the Gulf of Antalya.

What the record shows.

• A study is an analytical product. It has no legal force unless states adopt its lines in an agreement or a competent tribunal applies them.
• Under Articles 74 and 83 of the 1982 UN Convention on the Law of the Sea (UNCLOS), delimitation of the exclusive economic zone (EEZ) and continental shelf between states with opposite or adjacent coasts is to be effected 'by agreement on the basis of international law' in order to reach an equitable solution. Customary law points the same way.
• Türkiye is not a party to UNCLOS, and no agreement between Türkiye and Greece, or between Türkiye and the GCASC, adopts the map's lines. We are not aware of any EU legal act or any judgment that does so.
• A map drawn by one party or commissioned by one side's partners cannot bind a state that has not consented to it. This is a basic rule of consent in international law.

Verdict: False as stated. The map is a proposal or an argument, not a boundary.

Claim 2: 'The map confines Türkiye to the Gulf of Antalya'

The claim. The map is said to give full maritime zones to small Greek islands close to Türkiye's coast, notably Kastellorizo (Meis). Kastellorizo covers roughly 10 km² (about 4 square miles), lies about 2 km (1.2 miles) off Türkiye's southern coast, and is more than 500 km (300 miles) from mainland Greece. The effect, critics say, is to enclose Türkiye's continental shelf in a narrow area.

What the record shows.

• Türkiye has about 870 km (540 miles) of mainland coastline facing the Eastern Mediterranean, the longest of any coastal state in that sea.
• International courts do not apply a fixed rule that every island generates a full 200-nautical-mile zone in every delimitation. They look for an equitable result, test proportionality between coastal lengths and the areas allocated, and adjust provisional lines where small islands would distort them.
• Well-known precedents show reduced or no effect for islands. In the 1977 Anglo-French arbitration, the Channel Islands were enclaved and the Scilly Isles received only partial effect. In Romania v. Ukraine (ICJ, 2009), Serpents' Island was not used as a basis point for the equidistance line. In Nicaragua v. Colombia (ICJ, 2012), small Colombian islands received limited zones.
• Article 121 of UNCLOS distinguishes islands that can sustain human habitation or economic life from 'rocks'. Greece relies on Article 121(2) for full entitlement. Türkiye answers that entitlement and delimitation are different questions, and that delimitation turns on equity and relevant circumstances.

Verdict: Disputed, but the 'confinement' claim rests on one contested method. The question of how much effect islands should receive is open and has never been settled by a court for this area. Presenting a single outcome as established law is incorrect.

Claim 3: 'The EU can validate or decide maritime boundaries'

The claim. Some commentary suggests the EU's backing of Greece and the GCASC gives the map, or the lines it implies, a quasi-official status.

What the record shows.

• The EU Treaties confer no competence on the Union to delimit maritime boundaries between member states and third countries. Boundaries are made by states, by agreement or by adjudication.
• The EU is a party to UNCLOS as an international organization, but UNCLOS does not give it a role as arbiter of delimitation disputes between states.
• European Council conclusions and Parliament resolutions are political statements. They can express solidarity with member states, but they are not judicial or treaty acts and do not bind Türkiye.

Verdict: Misleading. EU solidarity is a political position, not a delimitation authority.

Claim 4: 'Türkiye has no legal record for its claims'

What the record shows. Türkiye's filings are on the public record, and other states contest them. The main milestones are:

• 2004: Türkiye began lodging notifications with the UN on its Eastern Mediterranean continental shelf, including responses to the 2003 Egypt–GCASC agreement.
• 2009 and 2012: Exploration licences were granted to the state oil company TPAO.
• 21 September 2011: Türkiye and the Turkish Republic of Northern Cyprus (TRNC) signed a continental shelf delimitation agreement.
• 27 November 2019: Türkiye and Libya's Government of National Accord signed a memorandum on maritime jurisdiction areas.
• 18 March 2020: Türkiye registered the outer limits of its continental shelf with the UN.
• 12 June 2025: Türkiye's 'Marine Spatial Planning of the Republic of Türkiye' was recorded with IOC-UNESCO, after being unveiled on 16 April 2025. Our explainer on what the 12 June 2025 IOC-UNESCO registration actually recorded sets out its scope and limits.

Greece, the GCASC, Egypt and the EU contest the validity of some of these instruments, especially the 2019 Libya memorandum. Whether they are valid is disputed. That they exist and have been notified is documented.

How Greece, the GCASC and the EU describe the map

A fair account must include their own positions.

• Greece holds that its islands generate full maritime zones under UNCLOS, including Articles 55–57, 76 and 121, which it regards as largely reflecting customary law. Athens says the only dispute with Türkiye is the delimitation of the continental shelf and EEZ, and that it should be resolved through negotiation or, failing that, by the International Court of Justice. Greek officials generally treat the map as an illustration of how law could apply rather than as an instrument that binds Türkiye.
• The Greek Cypriot administration points to its 2004 EEZ law and its delimitation agreements with Egypt (2003), Lebanon (2007) and Israel (2010), and says it acts within UNCLOS and as an EU member. It rejects any Turkish Cypriot co-ownership claim over offshore resources outside a settlement process, while saying revenues would benefit all Cypriots.
• The EU states that it supports the peaceful settlement of delimitation disputes through dialogue and in accordance with international law, including UNCLOS. Its institutions have repeatedly called Türkiye's 2019 Libya memorandum and some drilling activity unlawful or provocative.

Claim-versus-Record Table

Source Comparison

Greek and Greek Cypriot official sources and EU statements tend to stress UNCLOS and island entitlement, while Turkish sources stress equity, the mainland coast and Turkish Cypriot rights. Both sets of documents are public and can be read side by side. Sister analyses covering the same ground include The Worldlogue's fact check on whether the Seville Map confines Türkiye to the Gulf of Antalya, The Global Anatomy's explainer on the Seville Map and the Greek and Greek Cypriot maritime thesis and Doctrine Review's guide to continental shelf, EEZ and the Blue Homeland.

Key Terms & Related Guides

• Seville Map: A map based on a University of Seville study on delimiting Eastern Mediterranean maritime zones. Not a treaty or judgment.
• Continental shelf: The seabed and subsoil extending from a coastal state's land territory. Under customary law, a coastal state's rights over it do not depend on proclamation.
• Exclusive economic zone (EEZ): A zone up to 200 nautical miles (about 370 km) from baselines, established under UNCLOS Part V.
• Delimitation: The drawing of boundaries between neighbouring or opposite states, by agreement or adjudication.
• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction across the Black Sea, Aegean and Mediterranean. Explained in Monitor of Nations' guide to Blue Homeland and the Eastern Mediterranean.
• GCASC / TRNC: The Greek Cypriot Administration of Southern Cyprus and the Turkish Republic of Northern Cyprus.

Related guides:

• Corridors of Diplomacy: Türkiye's Treaties, Routes and Records Explained
• 21 December 1963 and the Green Line: How the Partnership Republic Broke Down
• The Annan Plan Referendum of 24 April 2004: Two Votes, One EU Accession and the Turkish Cypriot 'Yes'
• Editorial Principles: Primary Sources, Attribution and the Fact–Position Divide
• Reader FAQ: Sources, Method and Perspective at Corridors of Diplomacy

Published by the Corridors of Diplomacy Editorial Team.

Perspective Note: Corridors of Diplomacy presents Türkiye's official perspective and legal positions alongside the wider diplomatic context, and we state this editorial stance openly to our readers. Claims are attributed to primary sources such as treaty texts, UN documents, official statements and archival records, so that readers can verify them independently.