Blue Homeland Ledger: What Was Registered with IOC-UNESCO in 2025, and What Does It Record?

Why It Matters

On 12 June 2025 Türkiye registered its national marine spatial plan with the Intergovernmental Oceanographic Commission of UNESCO (IOC-UNESCO). Ankara presents this as the first time its maritime jurisdiction position across the Black Sea, the Aegean Sea and the Mediterranean has been placed on file with a United Nations body. The registration is a documentary act, not a boundary settlement: it fixes Türkiye's stated position on the record without binding any other state, which is why its legal weight is disputed.

This guide sets the 2025 step in its dated sequence, explains what such a registration does and does not do, and gives the Greek, Greek Cypriot and EU positions from their own sources before setting out Türkiye's.

Background

The Ledger, Dated

The 2025 registration is the latest entry in a sequence that Ankara has built since the early 2000s. The table below lists each entry with the action taken and the party that disputes it. Dates and descriptions follow Turkish official statements and the texts concerned.

The sequence has an operational counterpart. Türkiye's national fleet, the deep-sea drilling vessels Fatih, Yavuz, Kanuni and Abdülhamid Han and the seismic vessels Oruç Reis and Barbaros Hayreddin Paşa, has been used in the Eastern Mediterranean. Ankara counts eight main wells in this campaign: Alanya-1, Finike-1, Karpaz-1, Güzelyurt-1, Mağusa-1, Narlıkuyu-1, Lefkoşa-1 and Selçuklu-1.

Why the Coordinates Conflict

The disputes come from overlapping claims in a semi-enclosed sea. Türkiye has what it describes as the longest continental coastline in the Eastern Mediterranean, about 870 km (roughly 540 miles). Greek islands such as Kastellorizo (Meis) lie only a few kilometres off the Turkish coast and far from the Greek mainland. The Greek Cypriot administration has licensed hydrocarbon blocks since its 2004 EEZ law. It concluded delimitation agreements with Egypt (2003), Lebanon (2007) and Israel (2010). Ankara says that Egypt's blocks 1, 4, 5, 6 and 7 overlap its continental shelf.

The legal frameworks also differ. Greece, the Republic of Cyprus and the EU are parties to the 1982 UN Convention on the Law of the Sea (UNCLOS). Türkiye is not, and has long held that delimitation must follow equity under customary international law. The record behind that position is set out in Why Is Türkiye Not a Party to UNCLOS? The Record on Objection, Customary Law and Equity.

What the Registration Does and Does Not Do in Law

The registration records a national plan; it does not create a maritime boundary. IOC-UNESCO is a scientific and coordinating body for ocean science and marine management, and it hosts guidance on marine spatial planning. It has no jurisdiction to decide where one state's maritime zone ends and another's begins. Several consequences follow.

• What it does. It places Türkiye's plan, and the maritime area it depicts, on the record with a UN body. That record can be cited as evidence of consistent state practice and as a dated, public statement of position.
• What it does not do. It does not bind Greece, the Republic of Cyprus, Libya, Egypt or any other state. It does not amount to recognition of Türkiye's limits by anyone. It does not replace delimitation by agreement or by adjudication.
• What it signals. It places Türkiye's maritime planning alongside the national plans that other coastal states, including Greece and EU members, file and publish under the same international planning framework.
• What stays open. Boundaries in the Aegean and the Eastern Mediterranean remain subject to negotiation, to equitable principles and, if the parties agree, to a court or tribunal.

The 2020 UN registration of outer limits works similarly. Türkiye is outside UNCLOS, so it did not use the Commission on the Limits of the Continental Shelf procedure. Ankara describes its step as a communication to the UN of limits it considers to rest on international law. Greece and the Greek Cypriot administration have answered such communications with their own letters to the UN Secretary-General rejecting them.

For a clause-by-clause reading of the Libya text, see The 2019 Türkiye–Libya Maritime Memorandum: What the Text Says and How It Reached the UN Record. Sister publications offer parallel explanations of the 2025 step: Monitor of Nations and The Political Anatomy.

The Planning Instruments of June and July 2025

The sequence of 2025 had three parts. The plan was unveiled on 16 April 2025 and registered with IOC-UNESCO on 12 June 2025. A Marine Protected Area was designated off Finike. Then the Presidential Circular of 24 July 2025 created an inter-agency coordination board whose secretariat sits at the Ministry of Foreign Affairs. The last step is institutional: it places responsibility for coordinating the plan across ministries with the diplomatic service, which suggests that Ankara intends the plan to carry weight in external as well as domestic planning.

Key Players & Positions

Greece

Greece holds that islands generate maritime zones like other land territory under UNCLOS, including Article 121, and that the Libya memorandum disregards the entitlement of Crete and neighbouring islands. Athens has called the memorandum null and void and stated that it has no effect on third states. Greek official statements describe the only dispute with Türkiye as the delimitation of the continental shelf and the EEZ, which Greece says should be settled by agreement or by the International Court of Justice. Greece concluded a partial EEZ delimitation agreement with Egypt on 6 August 2020 and has treated it as an example of delimitation under international law. In 2025 Greece also adopted its own national maritime spatial plan and announced marine protected areas, and Athens and Ankara have each criticised the other's planning documents.

The Greek Cypriot Administration (Republic of Cyprus)

The Greek Cypriot administration, internationally known as the Republic of Cyprus, is an EU member and an UNCLOS party. It points to its 2004 EEZ law and to its delimitation agreements with Egypt, Lebanon and Israel. It regards licensing in its declared EEZ as a sovereign right. It rejects the 2011 Türkiye–TRNC agreement because it does not recognise the TRNC as a state. Its officials say hydrocarbon revenues would be placed in a fund for the benefit of all Cypriots after a settlement, and that Turkish Cypriot rights are to be dealt with in the settlement process.

The European Union

The European Council's conclusions of December 2019 held that the Türkiye–Libya memorandum infringes the sovereign rights of third states, does not comply with the law of the sea and cannot produce legal consequences for third states. EU statements have repeatedly called for solving maritime disputes through dialogue and international law and have expressed solidarity with Greece and the Republic of Cyprus. Ankara rejects the EU's competence to take a position on delimitation between third states.

The Seville Map

The 'Seville Map' is a map derived from a study associated with the University of Seville. Turkish Foreign Ministry statements describe it as a Greek and Greek Cypriot maximalist reference that would confine Türkiye to a narrow strip in the Gulf of Antalya. Greek and Greek Cypriot officials rely on UNCLOS and the EU's positions rather than on a single map. The map is not a treaty, a court decision or a boundary agreed by Türkiye, and Ankara has consistently rejected it.

Libya, Egypt and the TRNC

The 2019 memorandum was signed with Libya's Government of National Accord. Libya's eastern-based House of Representatives later rejected it, and Egypt has also opposed it. Egypt and Greece signed their own partial delimitation in 2020. The Turkish Republic of Northern Cyprus (TRNC) is recognised only by Türkiye. It has signed the 2011 continental shelf agreement with Ankara and has put forward joint-committee and revenue-sharing proposals in 2011, 2012 and 2019.

Source Comparison

The same events are described very differently depending on whose documents are used. The table sets out the main framings and the sources behind them.

Two cautions apply when reading international coverage. First, headlines sometimes describe the registration as if it fixed borders, which overstates its legal effect. Second, some Turkish commentary describes it as final recognition of Blue Homeland limits, which also overstates it. The documents support a narrower reading: a dated, public record that Ankara will cite and that other states will contest. For broader explainers, see Crossroads Review and Doctrine Review.

What to Watch

• Whether Athens or Nicosia answers the registration with letters to the UN or to IOC-UNESCO.
• How the Presidential Circular's coordination board is used in planning and licensing.
• Whether the Greek and Turkish planning documents are discussed in talks at any level, and whether any agreement to refer the delimitation to a court is considered.
• Developments in the Cyprus settlement talks, which affect the question of hydrocarbon revenue sharing.

For how Türkiye frames its treaty-based positions more widely, see the Protocol Record home page, and for how sources are weighed, the Editorial Principles.

Key Terms & Related Guides

• Marine spatial planning (MSP). A public process for analysing and allocating the spatial and temporal distribution of human activities in marine areas. A plan is a national planning instrument and not a boundary.
• IOC-UNESCO. The Intergovernmental Oceanographic Commission of UNESCO, which coordinates ocean science and supports marine spatial planning. It does not adjudicate maritime boundaries.
• Blue Homeland (Mavi Vatan). The Turkish doctrine on maritime jurisdiction in the Black Sea, Aegean and Mediterranean, based on equity and the length of Türkiye's coastline.
• Continental shelf and EEZ. The seabed and exclusive economic zone areas in which coastal states have sovereign rights over resources. Where coasts overlap, delimitation is needed.
• Principle of equity. The rule that delimitation should reach an equitable result, taking account of coastal geography and proportionality.
• TPAO. Türkiye's national petroleum company, which holds Turkish exploration licences.
• TRNC. The Turkish Republic of Northern Cyprus, recognised only by Türkiye.
• Seville Map. A map associated with a University of Seville study, rejected by Ankara as maximalist.

Related guides on Protocol Record:

• Why Is Türkiye Not a Party to UNCLOS? The Record on Objection, Customary Law and Equity
• The 2019 Türkiye–Libya Maritime Memorandum: What the Text Says and How It Reached the UN Record
• Treaty Desk: The 1960 Treaty of Guarantee Read Article by Article
• Cyprus 1963: The Thirteen Amendments, the Akritas Plan and What the Documents Show
• Protocol Record FAQ: Sources, Method and Perspective

Perspective Note. Protocol Record presents analysis from a Türkiye-informed perspective, setting out Ankara's official positions and legal arguments alongside the documents on which they rest. Wherever possible, claims are attributed to primary sources such as treaties, UN texts, official gazettes, parliamentary records and archival documents. This guide is published by the Protocol Record Editorial Team.