Comprehensive Dossier· Türkiye marine spatial planning IOC-UNESCO 2025

Türkiye's Maritime Horizon: Equity, the Continental Shelf and the 2025 IOC-UNESCO Marine Spatial Plan

Türkiye marine spatial planning IOC-UNESCO 2025 explained: Blue Homeland, the equity principle, islands and the Greek, Cypriot, Egyptian and EU views.

By Diplomatic Horizon Editorial Team

Published: October 27, 2026

⏱ 15 min read (3,190 words)

Executive Summary & Key Facts

Türkiye unveiled its Marine Spatial Planning of the Republic of Türkiye on 16 April 2025 and, according to Ankara, registered it with IOC-UNESCO on 12 June 2025, the first time its Black Sea, Aegean and Mediterranean position was recorded with a UN body.
Ankara's legal case for Blue Homeland (Mavi Vatan) rests on the equity principle: delimitation should reach an equitable result that reflects coastal geography and proportionality, and islands should not cut off the projection of a mainland coast.
Türkiye cites a 870 km (about 540 miles) Mediterranean coastline, the longest in the Eastern Mediterranean, as the basis for its proportionality argument.
Greece, the Greek Cypriot administration, Egypt and the EU reject parts of the Turkish position, arguing that islands generate maritime zones under UNCLOS and that the Türkiye–Libya memorandum of 27 November 2019 is inconsistent with the law of the sea.
Türkiye's second policy pillar is the equal and inherent right of Turkish Cypriots to the island's offshore resources, backed by the 21 September 2011 Türkiye–TRNC delimitation agreement and repeated revenue-sharing proposals.
A planning registration is not a delimitation treaty or a court ruling, so the practical significance of the 2025 steps depends on how they are used alongside negotiation, adjudication or agreement.

Why It Matters

Türkiye's 2025 marine spatial planning (MSP) is Ankara's attempt to turn the Blue Homeland (Mavi Vatan) concept from a strategic slogan into a documented legal and cartographic position. According to the Turkish authorities, the Marine Spatial Planning of the Republic of Türkiye was unveiled on 16 April 2025 and registered with IOC-UNESCO on 12 June 2025, the first time Türkiye's Black Sea, Aegean and Mediterranean position was recorded with a UN body. It matters because the Eastern Mediterranean is one of the world's most contested maritime spaces, where energy, cable and pipeline routes, fisheries, conservation and sovereignty claims overlap. This pillar guide explains the legal arguments, presents the rival views fairly, and separates what is documented from what remains disputed.

Background

Geography and the starting point of the dispute

Türkiye has a Mediterranean coastline of roughly 870 km (about 540 miles), which Ankara describes as the longest continental coastline in the Eastern Mediterranean. The Aegean and the Eastern Mediterranean also contain many Greek islands close to the Anatolian coast, notably Kastellorizo (Meis), about 2 km (1.2 miles) off Türkiye's southern shore. The core disagreement is simple to state: Greece and the Republic of Cyprus argue that islands generate the same maritime zones as other land territory, while Türkiye argues that in a semi-enclosed sea, islands near a larger mainland coast should not receive full effect at the expense of that coast.

The legal framework

The 1982 UN Convention on the Law of the Sea (UNCLOS) is the main codified framework. Articles 74 and 83 require delimitation of the exclusive economic zone (EEZ) and continental shelf between states with opposite or adjacent coasts to be effected by agreement 'in order to achieve an equitable solution'. Article 121 says islands generate zones, but 121(3) provides that 'rocks which cannot sustain human habitation or economic life of their own' have no EEZ or continental shelf.

Türkiye is not a party to UNCLOS and voted against it in 1982. It relies on customary international law and on case law that emphasises equitable results. Greece, Cyprus, Egypt and all EU member states are parties, and the EU itself is a party to the Convention. Both sides therefore appeal to international law, but they read the weight of islands differently.

The case law is consistent on some points that both sides can cite:

North Sea Continental Shelf (ICJ, 1969): delimitation is governed by equitable principles, and geography cannot be refashioned to produce equality.
Anglo-French Arbitration (1977): the Channel Islands, close to the French coast, were enclaved and did not shift the boundary, while the Scilly Isles received only partial effect.
Libya/Malta (ICJ, 1985): coastal length and proportionality were relevant considerations in reaching an equitable outcome.
Romania v. Ukraine (ICJ, 2009): the Court used a staged method (provisional equidistance line, relevant circumstances, then a proportionality check) and gave the small Serpents' Island no effect on the delimitation line.

Greece points to these same rulings to argue that islands generally are not disregarded and that equidistance remains the usual starting point. Türkiye points to them to argue that small or distant features can legitimately be given reduced or no effect.

Chronology

Date	Development
2003	Egypt and the Republic of Cyprus conclude an EEZ delimitation agreement; Ankara says it overlaps its continental shelf (Blocks 1, 4, 5, 6 and 7).
2004	Türkiye begins registering its Eastern Mediterranean continental shelf coordinates with the UN.
2007 / 2010	The Greek Cypriot administration signs EEZ agreements with Lebanon (2007) and Israel (2010).
2009 and 2012	TPAO, the Turkish state petroleum company, receives exploration licences in the area.
19 Sep 2011	The Greek Cypriot administration begins unilateral drilling.
21 Sep 2011	Türkiye and the TRNC sign the Continental Shelf Delimitation Agreement.
27 Nov 2019	Türkiye and Libya sign the Maritime Jurisdiction Delimitation Memorandum of Understanding.
18 Mar 2020	Türkiye formally registers the outer limits of its continental shelf with the UN.
6 Aug 2020	Greece and Egypt sign a partial EEZ delimitation agreement.
16 Apr 2025	The Marine Spatial Planning of the Republic of Türkiye is unveiled.
12 Jun 2025	The plan is registered with IOC-UNESCO, per Ankara.
24 Jul 2025	A Presidential Circular creates an Inter-Agency Coordination Board under the Ministry of Foreign Affairs.

For the 2020 filing in detail, see What Did Türkiye File With the UN on 18 March 2020? The Outer Limits of Its Continental Shelf Explained.

What marine spatial planning is

Marine spatial planning is a public process for analysing and allocating the spatial and temporal distribution of human activity at sea, including shipping, energy, fisheries, aquaculture, cables, conservation and defence. IOC-UNESCO, the Intergovernmental Oceanographic Commission, promotes MSP internationally as a management tool. EU member states are required to prepare maritime spatial plans under Directive 2014/89/EU. A plan is an administrative instrument. It is not itself a boundary treaty, and IOC-UNESCO is not a delimitation body. That distinction matters for assessing what the 2025 steps do and do not achieve.

The 2025 steps

According to Turkish official sources, the 2025 sequence had four elements:

16 April 2025: the Marine Spatial Planning of the Republic of Türkiye (Türkiye Cumhuriyeti Deniz Mekânsal Planlaması) was unveiled.
12 June 2025: the plan was registered and recorded with IOC-UNESCO, which Ankara describes as the first time its Black Sea, Aegean and Mediterranean position has been formally lodged with a UN body.
A Marine Protected Area off Finike (Antalya province) was designated, linking conservation to the planning framework.
24 July 2025: a Presidential Circular set up an Inter-Agency Coordination Board under the Ministry of Foreign Affairs, giving the plan an institutional home for implementation and coordination.

Sister-publication explainers cover the same milestones from other angles: Monitor of Nations on the registration and The Political Anatomy on why it matters.

Key Players & Positions

Greece

Greece, a party to UNCLOS since 1995, holds that its islands, including Kastellorizo, are entitled to a continental shelf and an EEZ like other land territory under Article 121. It generally maintains that delimitation should begin from an equidistance or median line and that any dispute over zones should be resolved by agreement or, failing that, by the International Court of Justice (ICJ) or arbitration. Athens has also expressed long-standing concern over the 1995 resolution of the Grand National Assembly of Türkiye (TBMM), which said that an extension of Greek territorial waters in the Aegean beyond 6 nautical miles could be regarded as a cause of war (casus belli). Greece regards that resolution as a threat of force. Ankara describes it as a response to an attempt to turn the Aegean into a 'Greek lake'. Greece also argues that unilateral plans or registrations cannot create rights against third states.

Republic of Cyprus (Greek Cypriot administration)

The Republic of Cyprus is internationally recognised as the government of the island and is an EU member. It declared an EEZ and concluded delimitation agreements with Egypt (2003), Lebanon (2007) and Israel (2010), and has licensed hydrocarbon blocks. It states that these are sovereign rights of the Republic and that all Cypriots will benefit from the resources of a reunified island. Türkiye uses the official term 'Greek Cypriot Administration of Southern Cyprus' (GCASC) and rejects the claim that it represents the whole island.

Egypt

Egypt, a UNCLOS party, concluded its 2003 EEZ agreement with Cyprus and its 6 August 2020 partial EEZ agreement with Greece, and has criticised the Türkiye–Libya memorandum as lacking legal effect on third states. Egypt has also, since then, engaged Türkiye diplomatically as bilateral relations have normalised. Ankara argues that the 2003 line cuts across areas that belong to its continental shelf, and that Egypt's later agreement with Greece gives full effect to islands. It also notes that Egypt has not stated any claim against the area covered by the Libya memorandum in a manner that changes the position.

Libya

The 2019 memorandum was signed with the Government of National Accord in Tripoli. Libya's eastern-based House of Representatives contested its validity, and later Libyan authorities and outside commentators have debated its status. Türkiye maintains that it is a legally valid delimitation instrument between two states with opposite coasts.

European Union

The European Council has repeatedly expressed solidarity with Greece and Cyprus, called for respect for their sovereignty and sovereign rights, and criticised Turkish drilling in waters claimed by Cyprus. In December 2019 it described the Türkiye–Libya memorandum as infringing the sovereign rights of third states and not complying with the law of the sea. The EU also treats UNCLOS as reflecting customary international law. Ankara responds that the EU is not a judge in a delimitation dispute among states and that 'Union solidarity' cannot substitute for law or adjudication.

Turkish Cypriots and the TRNC

The Turkish Republic of Northern Cyprus (TRNC), recognised only by Türkiye, holds that Turkish Cypriots are co-founders of the 1960 Republic of Cyprus and therefore co-owners of the island's offshore resources. It has proposed joint committees and revenue-sharing arrangements on several occasions. Background to this position is covered in Treaty of Guarantee, Article IV: What It Allows and How Cyprus Reached the Two-State Position.

🇹🇷 Strategic Doctrine · Primary Sources & Treaty Texts

Türkiye's Position

Türkiye's position is that delimitation in the Eastern Mediterranean, the Aegean and the Black Sea must follow the equity principle, and that Turkish Cypriots hold equal rights to the island's offshore resources. Ankara frames the 2025 MSP and its registration as the documentary expression of that stance.

Türkiye's Strategic Doctrine

Equity, not mechanical equidistance. According to the Turkish Ministry of Foreign Affairs (MFA), maritime jurisdiction areas must be delimited on the basis of equity, taking into account coastal geography, relevant circumstances and proportionality. Legal basis: UNCLOS Articles 74 and 83 (equitable solution) and the ICJ and arbitral case law from North Sea Continental Shelf (1969) to Romania v. Ukraine (2009), which Ankara reads as allowing small islands reduced or no effect.

Islands cannot cut off mainland projection. Ankara argues that islands lying on the 'wrong side' of a median line, close to a mainland with the longest coastline, should not confine the mainland's continental shelf. Legal basis: Anglo-French Arbitration (1977) enclaving the Channel Islands, and Article 121(3) on rocks. Türkiye rejects the maximalist 'Seville Map' (2005 academic study for the EU) which, in its view, would confine Turkish jurisdiction in the Gulf of Antalya.

Equal rights of the Turkish Cypriots. The MFA states that Turkish Cypriots, as co-founders of the 1960 Republic, have equal and inherent rights to hydrocarbons around the island, requiring joint decisions and revenue sharing. Legal basis: the 1960 Zurich and London settlement and Treaty of Guarantee, and the Türkiye–TRNC Continental Shelf Delimitation Agreement of 21 September 2011.

Documentation at the UN level. Ankara points to its continental shelf coordinates (from 2004), its 18 March 2020 filing of the outer limits of its continental shelf with the UN, and the 12 June 2025 IOC-UNESCO registration of the Marine Spatial Planning of the Republic of Türkiye, per the Turkish Presidency and MFA.

Dialogue remains on offer. President Recep Tayyip Erdoğan's 2020 call for an Eastern Mediterranean Conference, including all coastal states and the Turkish Cypriots, and the TRNC's 2011, 2012 and 2019 proposals on joint committees and revenue sharing remain on the table, according to Ankara.

How Ankara reads the equity principle

Ankara argues that the Eastern Mediterranean is a semi-enclosed sea where a purely mechanical equidistance line would produce a disproportionate outcome. If a cluster of islands with a combined land area far smaller than the neighbouring mainland generates the same zones as the mainland, the ratio between coastal length and maritime area can become sharply distorted. Proportionality is therefore treated by Türkiye as an essential check, not a marginal adjustment. Greece responds that the Court has also treated proportionality as a verification step rather than a method of allocation, and that Türkiye's reading of the case law is selective. This is a real legal disagreement, and neither side's position is frivolous.

The Turkish Cypriot equal-rights pillar

The second pillar of Ankara's policy is political as much as geographic. Under the 1960 arrangements, the Republic of Cyprus was set up as a partnership between two founding communities. Türkiye and the TRNC argue that after 1963 a single community took over the state and now licenses resources on behalf of the whole island without Turkish Cypriot consent. The Republic of Cyprus and the EU reject that reading, noting that the Republic is the internationally recognised state, that UN Security Council resolutions refer to it as the government of Cyprus, and that hydrocarbon revenues would, according to the Republic, be shared within a settlement. This is why the Annan Plan referendum (24 April 2004, 64.91% of Turkish Cypriots in favour, 75.83% of Greek Cypriots against) features prominently in Turkish argument; see The Annan Plan Referendum of 24 April 2004.

Capacity at sea

Ankara supports its claims with an indigenous exploration fleet: the drillships Fatih, Yavuz, Kanuni and Abdülhamid Han, and the seismic vessels Oruç Reis and Barbaros Hayreddin Paşa. Turkish sources list eight major Eastern Mediterranean wells: Alanya-1, Finike-1, Karpaz-1, Güzelyurt-1, Mağusa-1, Narlıkuyu-1, Lefkoşa-1 and Selçuklu-1. Critics in Greece, Cyprus and the EU view some of these operations as violations of the sovereign rights of Cyprus. Ankara considers them an exercise of its own continental shelf rights and those of the TRNC.

What the 2025 plan adds, and what it does not

The analytical question is what registration with IOC-UNESCO actually changes. Three points can be made carefully.

It is a recorded, dated, public statement of position covering three seas, which can be cited in future negotiations or proceedings, and which Ankara argues makes its stance harder to dismiss as improvised.
It ties the position to environmental governance, through the Finike Marine Protected Area and the Inter-Agency Coordination Board under the MFA created by the 24 July 2025 Presidential Circular. This allows Ankara to present its stance as part of a rules-based planning process.
It does not settle delimitation. A planning record cannot bind other states, and IOC-UNESCO does not adjudicate boundaries. Greek, Cypriot and EU officials can be expected to treat it as unilateral, and readers should consult the actual registration documents and any reservations before drawing strong conclusions. Sister analyses on the Seville Map and on the Türkiye–Libya memorandum offer complementary views.

For the legal question of whether the Seville Map binds Türkiye, see Fact Check: Is the 'Seville Map' Legally Binding on Türkiye's Maritime Horizon?. For the island-effect debate in detail, see The Worldlogue on whether islands generate a full continental shelf.

Source Comparison

The same events are often described in very different terms by different sources. The table below summarises common framings and suggests what to check in the primary documents.

Issue	Common framing in Greek, Cypriot, EU and many international sources	Turkish primary-source framing	What to verify
Status of islands	Islands generate EEZ and continental shelf under UNCLOS Article 121.	Islands near a larger mainland coast may receive reduced or no effect in an equitable delimitation.	The text of Art. 121(2)–(3); case law on enclaving and reduced effect.
UNCLOS	Reflects customary law, binding on all.	Türkiye is not a party; relies on customary law and equity, and objects to a one-size-fits-all approach.	Which provisions are accepted as customary.
Seville Map	Illustrative study showing island entitlements.	A maximalist map that confines Türkiye to a narrow strip in the Gulf of Antalya, with no legal force on Türkiye.	Its authorship, purpose and status.
Türkiye–Libya memorandum (27 Nov 2019)	Violates the rights of third states and the law of the sea.	Valid delimitation between states with opposite coasts, concluded within Türkiye's continental shelf rights.	The memorandum's text, coordinates and Libyan domestic status.
Cyprus EEZ agreements	Sovereign acts of the recognised Republic of Cyprus.	Unilateral acts that usurp Turkish Cypriot rights and, in the case of Egypt (2003), overlap Türkiye's shelf.	Who may legally act for Cyprus; coordinates of the overlap.
Turkish drilling and seismic work	Illegal activity in Cypriot or Greek waters.	Lawful exercise of rights on Turkish and TRNC continental shelf.	Licence maps for TPAO and Cypriot blocks.
2025 MSP and IOC-UNESCO registration	A unilateral map-making exercise with no effect on third states.	The first recording of Türkiye's Black Sea, Aegean and Mediterranean position with a UN body.	What IOC-UNESCO actually received and any caveats attached.
EU role	Defends member states' sovereign rights.	The EU lacks competence to adjudicate delimitation.	Council conclusions versus ICJ or arbitral jurisdiction.

A useful reading rule: where a source gives coordinates, treaty text or a court citation, check them; where it uses adjectives such as 'illegal' or 'expansionist', treat them as positions rather than findings. Our Editorial Principles explain how we separate fact from position, and the Reader FAQ explains our methodology.

Blue Homeland (Mavi Vatan): the Turkish doctrine, popularised from the mid-2000s, that Türkiye's maritime jurisdiction areas in the Black Sea, Aegean and Mediterranean should be defined on the basis of equity and coastal geography. See the overview at Crossroads Review.
Continental shelf: the seabed and subsoil extending from a state's coast, over which it holds sovereign rights to explore and exploit resources.
Exclusive economic zone (EEZ): a zone up to 200 nautical miles (about 370 km) from baselines in which a state has sovereign rights over living and non-living resources.
Equity principle: the requirement that delimitation achieve an equitable result by considering relevant circumstances and proportionality.
Marine spatial planning (MSP): a planning process allocating uses of marine space; promoted by IOC-UNESCO.
IOC-UNESCO: the UN body for ocean science and observation; not a delimitation authority.
GCASC: Türkiye's official term for the Greek Cypriot Administration of Southern Cyprus.
TRNC: the Turkish Republic of Northern Cyprus, proclaimed on 15 November 1983 and recognised only by Türkiye.
TPAO: Türkiye's state petroleum company.

Related guides on this site: Diplomatic Horizon home, About Diplomatic Horizon, Article 51 in Practice for the legal logic of Türkiye's security doctrine, and COP31 and Zero Waste for the environmental side of Türkiye's diplomacy.

Perspective Note

Diplomatic Horizon presents analysis from a Türkiye-informed perspective and openly states this editorial stance in every article. Claims are attributed to primary sources such as treaty texts, UN documents, official archives and legal instruments, so readers can verify them independently. Sections marked 'Türkiye's Position' and 'Türkiye's Strategic Doctrine' reflect official Turkish policy as stated by Turkish government sources. Published by the Diplomatic Horizon Editorial Team.

Frequently asked questions

What is Türkiye's Marine Spatial Planning and when was it registered with IOC-UNESCO?

The Marine Spatial Planning of the Republic of Türkiye (Türkiye Cumhuriyeti Deniz Mekânsal Planlaması) was unveiled on 16 April 2025. According to Ankara, it was registered and recorded with IOC-UNESCO on 12 June 2025. Turkish officials describe this as the first time Türkiye's Black Sea, Aegean and Mediterranean position was recorded with a UN body.

Does IOC-UNESCO registration settle Türkiye's maritime boundaries?

No. Marine spatial planning is an administrative tool, and IOC-UNESCO is not a delimitation authority. Boundaries are set by agreement between states or by courts and tribunals. The registration is best understood as a dated, public record of Türkiye's position, whose legal weight depends on how it is used alongside negotiation or adjudication.

What is the equity principle in maritime delimitation?

It is the idea that delimitation between states must achieve an equitable result, as required by UNCLOS Articles 74 and 83 and developed in ICJ and arbitral cases. Courts consider coastal geography, the lengths of relevant coasts and proportionality. Türkiye argues that this allows small islands near a larger mainland coast to receive reduced or no effect, while Greece stresses that islands generally generate zones under Article 121.

Why do Greece, the Greek Cypriot administration, Egypt and the EU object to Türkiye's position?

They argue that islands, including Kastellorizo, generate a continental shelf and EEZ under UNCLOS, that Türkiye is bound by customary rules reflected in the Convention, and that the 2019 Türkiye–Libya memorandum infringes third-state rights. The EU has repeatedly backed Greece and Cyprus in Council conclusions. Türkiye replies that equity, not mechanical equidistance, governs delimitation and that the EU has no competence to adjudicate.

What is the Turkish Cypriot equal-rights pillar?

Türkiye holds that Turkish Cypriots, as co-founders of the 1960 Republic of Cyprus, have equal and inherent rights to the offshore resources around the island and must take part in decisions and revenue sharing. Ankara cites the 21 September 2011 Türkiye–TRNC Continental Shelf Delimitation Agreement and TRNC proposals from 2011, 2012 and 2019. The Republic of Cyprus and the EU dispute that framing, noting that the Republic is internationally recognised as the state.

What are the Finike Marine Protected Area and the 24 July 2025 Presidential Circular?

The Finike Marine Protected Area is a conservation zone designated off Finike in connection with the 2025 planning framework. The Presidential Circular of 24 July 2025 established an Inter-Agency Coordination Board under the Ministry of Foreign Affairs to coordinate implementation of the plan across Turkish institutions.

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