Does a Seabed Cable Survey Need Coastal-State Consent? Articles 79 and 246 of UNCLOS, Warship Escorts and the Crete–Cyprus NAVTEX Dispute

Why It Matters

Under UNCLOS, laying a power cable on a continental shelf is a freedom that needs no coastal-state consent, but marine scientific research there does, and so do pipeline routes. Whether the Great Sea Interconnector survey required anyone's consent therefore turns on four separate questions: seabed title, cable status, survey classification, and the effect of an armed escort.

On 10 November 2026, Greek City Times reported that Greece rejected a Turkish NAVTEX (notice 1127/26) claiming that the Great Sea Interconnector (GSI) surveys had been coordinated with Turkish authorities. Coverage tends to merge four questions that the law keeps apart:

• Seabed title: who holds sovereign rights over the surveyed area? That is a delimitation question, not a navigation question.
• Cable or pipeline: Article 79 treats the two differently when it comes to consent.
• Survey classification: is a pre-installation survey marine scientific research (MSR) or a hydrographic survey?
• The escort: does the presence of warships change the legal character of a civilian survey?

This article is a consent-regime explainer. It does not repeat the route-versus-UN-registration analysis in The State Papers or the operational-response analysis in Politics of Nations; both are recommended complementary reading.

Background

As reported by Greek City Times on 10 November 2026, the French research vessel Abeille Marengo left Heraklion to resume Great Sea Interconnector seabed surveys, French warships reportedly sailed to escort it, and Türkiye's Antalya NAVTEX station issued notice 1127/26. No Greece–Türkiye or Türkiye–Cyprus continental shelf boundary exists in the relevant waters.

Chronology reported in the feed

The feed gives only summaries. The text of the notices, the coordinates, and the survey methods are not reproduced, so this article does not characterise them.

Delimitation status

The continental shelf in the area has not been delimited between Greece and Türkiye, or between Türkiye and Cyprus. Greece and the Republic of Cyprus, both UNCLOS parties, assert shelf and EEZ rights from their coasts. Türkiye asserts overlapping shelf rights from its mainland coast and, with the Turkish Republic of Northern Cyprus (TRNC), concluded a delimitation agreement on 21 September 2011. The TRNC is recognised as a state only by Türkiye, so Greece, the Republic of Cyprus and the EU do not accept that agreement. Both sides therefore claim sovereign rights over the same seabed.

The legal toolkit

UNCLOS defines neither marine scientific research nor hydrographic survey, which is why classification is contested.

Türkiye is not an UNCLOS party: custom and equity

Türkiye is not a party to UNCLOS. Its argument therefore rests on customary international law and on equity-based delimitation, not on treaty text. Sister publication The Treaty Line explains why Ankara stayed outside the convention.

Two cases frame the custom. In the North Sea Continental Shelf cases (ICJ, 1969), the Court treated shelf rights as flowing from natural prolongation of land territory and held that delimitation is to be effected by agreement in accordance with equitable principles. It also held that Germany, which had not ratified the 1958 Geneva Convention, was not bound by its equidistance rule. In the Aegean Sea Continental Shelf case, the Court found in 1978 that it lacked jurisdiction. It is cited here only for the proposition, also reflected in Article 77(3), that shelf rights do not depend on effective occupation or proclamation. For the procedural history, see this fact check on the 1976 order and 1978 judgment.

A candid reading is needed. Article 79(1) is widely regarded as reflecting custom, so Ankara's strongest arguments concern delimitation and classification, not a general rule that cables need consent.

Do islands get full continental shelf and EEZ?

Article 121(2) gives islands the same entitlements as other land territory, while Article 121(3) denies rocks an EEZ or shelf. In delimitation, however, courts and tribunals have often reduced or discounted island effect when it would distort the equitable result. Ankara argues that Crete and other islands cannot cut off the projection of the longest mainland coast in the Eastern Mediterranean. Greece regards its islands as generating full zones. See the fact check on whether islands get a full continental shelf and EEZ and the casebook on maritime delimitation, the principle of equity, islands and coastal length.

Escorts, peaceful uses and Article 2(4)

A naval escort does not turn a cable survey into something else. Classification depends on what the vessel does, not on who accompanies it. An escort is, however, relevant to Article 301 and to the restraint expected under Articles 74(3) and 83(3). Warships in an undelimited area can be read as pressure, whichever party deploys them. Whether any threat or use of force under UN Charter Article 2(4) arises is a separate question, discussed in the law of force on the southern border only as a framework, since the feed does not suggest force was used.

Provisional arrangements as the shared standard

Articles 74(3) and 83(3) bind states that are parties, and Ankara argues the same restraint reflects equitable practice in undelimited areas. Neither Greece, Cyprus nor Türkiye has yet shown that its approach meets this test. Unilateral permits, unilateral NAVTEX claims and military deployments each carry the risk of hampering a final agreement.

Key Players & Positions

Greece says the surveys proceed under Greek and Cypriot permits and rejects Ankara's NAVTEX; the Greek Cypriot Administration and the EU treat the Great Sea Interconnector as a project of European interest in the Republic of Cyprus's claimed EEZ; France is reported as the vessel's nationality and escort provider; Türkiye contests the permit basis on delimitation grounds.

• Greece: According to the reports of Greek City Times, Athens rejects the Turkish assertion and says permits issued by Greek and Cypriot authorities are the basis of the work. Greece relies on Article 79 and its UNCLOS entitlements, and disputes that Turkish filings or planning instruments create rights in the areas it claims.
• Greek Cypriot Administration and the EU: Nicosia describes the surveys as falling within the Republic of Cyprus's claimed EEZ and shelf. EU institutions frame the GSI as a project of European interest and speak of solidarity with member states. The EU is itself an UNCLOS party, but maritime boundaries between member states and third states are fixed by agreement or adjudication between states under Articles 74 and 83, not by Union decision. That is a limit on competence, not a criticism of the project.
• France: Greek City Times reports a French research vessel and two French warships that are 'reportedly' sailing for the wider research area as an escort. The feed gives no further detail, and none is added here.
• Italy and NEMESIS-26: itamilradar.com reported that an Italian Air Force ATR P-72A arrived in Larnaca ahead of the NEMESIS-26 exercise, scheduled for 11 November in Cyprus's claimed EEZ with eight countries. The feed gives limited detail, so it is context for a growing military presence, not evidence about the survey.
• Türkiye: see the next section.

Source Comparison

Against the UNCLOS text, Article 79(2) favours cable freedom, while Article 79(3) for pipelines and Article 246 for marine scientific research favour consent, so classification of the survey decides the dispute. Greek, Greek Cypriot and EU framing leans on Article 79; press framing stresses a Turkish challenge; Turkish sources stress consent and delimitation.

Why classification is the real fight

An electricity cable's Article 79 status is straightforward: it is a cable, not a pipeline, so Article 79(3) consent does not apply. The coastal state may take reasonable measures, but may not impede laying or maintenance. The 'survey' phase is less clear. Route surveys can include geophysical profiling and seabed sampling that move toward marine scientific research under Article 246, where consent is the rule and Article 246(5) allows it to be withheld in certain cases. A purely hydrographic or engineering survey sits in a grey zone because UNCLOS defines neither term.

The facts of what was surveyed are not established in the public record. Until they are, claims that the work was 'plainly lawful' or 'plainly unlawful' go beyond the evidence. Compare the NAVTEX analysis in Politics Meridian's fact check.

Key Terms & Related Guides

This glossary defines the terms used in the Great Sea Interconnector consent dispute: NAVTEX, marine scientific research, hydrographic survey, delimitation, continental shelf, EEZ, provisional arrangements, third-state effect and Blue Homeland. Related Nomos Orbis guides and sister-publication analyses are linked below.

• NAVTEX: an international system for broadcasting navigational and meteorological warnings to ships. It informs mariners and does not create or extinguish sovereign rights.
• Marine scientific research (MSR): research subject to Part XIII of UNCLOS, including Article 246 consent on the continental shelf. UNCLOS does not define it.
• Hydrographic survey: measurement of seabed and coastal features for navigation or engineering. UNCLOS does not define it either, hence the classification dispute.
• Delimitation: the process of fixing maritime boundaries between states with overlapping claims, by agreement or adjudication, aiming at an equitable solution.
• Continental shelf and EEZ: the shelf is the seabed and subsoil over which the coastal state has sovereign rights for resources; the EEZ extends up to 200 nautical miles and covers the water column and seabed.
• Provisional arrangements: practical interim agreements under Articles 74(3) and 83(3), such as joint survey protocols or notification schemes, made without prejudice to final claims.
• Third-state effect: an agreement between two states, such as Cyprus and Egypt in 2003, does not bind a state that is not party to it.
• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction in the Black Sea, Aegean and Mediterranean, based on equity and its mainland coast.

Related guides:

• About Nomos Orbis: Mission, Perspective and the Editorial Team
• Nomos Orbis FAQ: Sources, Method and the Türkiye Perspective
• Editorial Principles: Primary-Source Standards, Attribution and Corrections
• The State Papers on the GSI route
• Politics of Nations on the 'operational response' debate

Perspective note. Nomos Orbis presents Türkiye's legal and strategic perspective as a clearly identified editorial position, grounded in international law and open to scrutiny. Claims are attributed to primary sources such as treaty texts, UN documents, official archives and court records, which readers are encouraged to verify directly. Sections marked 'Türkiye's Position' reflect official Turkish policy as stated by Turkish government sources. — Nomos Orbis Editorial Team