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Undersea Cables
File image of the Nexans Electra
The Department of Transport has been advised that Nexans will perform undersea cable operations for the Celtic Interconnector Designated Activity Company (CIDAC) as part of the Celtic Interconnector Project from Monday 2 November for approximately four days, subject to weather…
Global Sentinel specialist subsea telecommunications cable-laying ship
Ireland and Britain have introduced a new incident-reporting protocol for subsea cables and conducted a joint security exercise, marking a further step in efforts to protect critical maritime infrastructure around the two countries. The developments were outlined by Minister for…
Proposed PISCES subsea cable route from Galway to Portugal, with branches to France and Spain
A proposed subsea telecommunications cable linking Galway with Portugal, Spain and France has taken a further regulatory step, with an application lodged with the Maritime Area Regulatory Authority (MARA) for consent to install and operate the system. PISCES Cable System…
ICCB marine operations at East Anglia TWO offshore wind farm cable landfall off Suffolk
Dublin-based Irish Commercial Charter Boats has played a key marine operations role in a record-breaking 1.8-kilometre cable duct installation for ScottishPower Renewables' East Anglia TWO offshore wind farm off Suffolk. Dublin-based Irish Commercial Charter Boats (ICCB), headed by Eoin Grimes,…
Marine survey jack-up platform and support vessel off Ireland's south coast during EirGrid offshore wind investigations
Almost 70,000 hours of marine and coastal survey work have been completed off Ireland's south coast as EirGrid advances plans to connect 900MW of offshore renewable energy to the national electricity grid. EirGrid has completed its 2026 marine and coastal…
Green Rebel’s MV Roman Rebel will be engaged in offshore survey operations in the Irish Sea during the first half of November
The Department of Transport advises that Green Rebel is undertaking nearshore and offshore survey operations on behalf of ACSM and EirGrid off the coast of Rush in north Co Dublin. These survey operations will consist of hydrographic and geophysical works…
Energy Warning — Dr Brendan Flynn of the University of Galway highlights threats to Ireland's subsea energy infrastructure at Atlantic Summit Galway 2026. Photo: Andrew Downes/Xposure
Damage to essential infrastructure along the seabed off Ireland could lead to an energy crisis at an “unprecedented scale”, a University of Galway academic has warned. University of Galway senior lecturer Dr Brendan Flynn told the Atlantic Summit that in…
Looking Offshore: EirGrid representatives survey the south coast as the grid operator opens consultation on infrastructure to connect future offshore wind generation
EirGrid has launched a 12-week public consultation on proposed electricity grid infrastructure in Cork and Wexford to connect future offshore wind generation off Ireland’s south coast. The consultation, which opened on Tuesday (15 September) and runs until 8 December, sets…
Map showing MDM's planned Narwhal 1 and Narwhal 2 transatlantic subsea fibre cable routes between Ireland and the United States
Two new subsea fibre-optic cable systems linking Ireland directly with the United States are planned in a $500 million investment, with landings proposed in Galway and on Ireland’s south coast. Irish subsea cable specialist MDM has announced plans for the…
Cable Pioneer — CS Faraday, the purpose-built cable ship constructed for Siemens Brothers and launched in 1874, was contracted to lay the early Commercial Cable Company transatlantic cables.
Tales of the ships that laid Waterville’s cables off the Kerry coast will be told during several special events planned for Heritage Week 2026 this month.Friends of Waterville Cable Station are organising two special events on Saturday, August 22nd. The first…
Harbour Posting — A High Court notice concerning EirGrid marine survey operations in Dublin Bay displayed at Dún Laoghaire Harbour. The notice includes a map of the licensed survey corridor. Photo: Afloat
A High Court notice relating to EirGrid's marine survey operations in Dublin Bay remains on public display at Dún Laoghaire Harbour. The notice, dated 14 May 2026, is attached to railings overlooking the marina and contains details of court orders…
Works will be undertaken by the vessel Seapiper
The Department of Transport has been advised that Boskalis will perform subsea rock installation for cable protection on behalf of Nexans for CIDAC as part of the Celtic Interconnector Project. The operations will be located along the planned route of…
Cable Focus — Minister for Defence Helen McEntee TD examines a section of subsea telecommunications cable with Aurora Telecom's Sean O'Donnell during the Subsea Cable Security and Resilience Symposium at Valentia Island, Co Kerry. Photo: Domnick Walsh/Eye Focus Ltd.
New research led by Britain’s National Oceanography Centre (NOC) has found that the greatest risks to subsea telecommunications cables lie close to island coastlines. A study jointly led by Dr Isobel Yeo and Dr Mike Clare at the NOC provides…
TechWorks Marine logo
The Department of Transport has been notified by TechWorks Marine that they will deploy a seabed frame as part of a nearshore ocean current measurement campaign for the Celtic Interconnector Project. Works were set to begin on Monday 8 June…
Greenlink Interconnector logo
A geophysical survey of the Greenlink Interconnector undersea cable route between Ireland and Wales will be undertaken in the Irish Sea from this week. The environmental video survey, using a drop-down camera along perpendicular transects at 12 stations, with three…
File image of the Van Oord vessel Calypso
The Department of Transport has been advised that Van Oord will perform cable operations on behalf of Nexans for CIDAC as part of the Celtic Interconnector Project. This work will be undertaken along a segment of the undersea cable route…

Undersea Cables

Undersea cables are vital to Ireland's connectivity, facilitating high-speed internet, telecommunications, and energy transmission. These cables traverse the Irish Sea, connecting Ireland to the United Kingdom and continental Europe, and play a crucial role in global communications.

Submarine Communications Cables:
Ireland is strategically positioned along major transatlantic communication routes. Approximately 75% of transatlantic cables pass near Irish waters, underscoring the nation's significance in global data transmission.
These cables are typically as wide as a garden hose, with the filaments that carry light signals being extremely thin—roughly the diameter of a human hair. They are sheathed in layers of insulation and protection, with cables laid nearer to shore using extra layers of armoring for enhanced protection.

Energy Interconnectors:
In addition to communication cables, undersea interconnectors are being developed to enhance energy security and support the transition to renewable energy sources. The UK has approved the construction of five new subsea interconnector cables to boost the grid's flexibility amidst rising renewable energy. These projects will link the UK with wind farms in Belgium and the Netherlands, and connect England with Germany, Wales with Ireland, and Scotland with Northern Ireland. The cables, with a combined 6GW capacity, are expected to be operational by 2032, increasing the UK's total interconnector capacity to 18GW.

Security Concerns:
The strategic importance of these undersea cables has raised security concerns. Incidents in the Baltics have heightened awareness about the potential risks to subsea infrastructure. Ireland's historical neutrality and limited defense resources have led to calls for enhanced maritime security and defense investments, including modern surveillance technology and international cooperation. The government's response includes participation in EU security projects and collaboration with neighboring countries on maritime security.

In November 2024, a Russian spy ship, the Yantar, was escorted out of the Irish Sea by the Irish navy after it was found patrolling an area with critical submarine pipelines and cables. The vessel's presence heightened concerns due to its proximity to interconnector cables vital for internet services linking Ireland to the UK, operated by major tech companies such as Google and Microsoft.

Regulatory and Policy Framework:
The protection and maintenance of undersea cables fall under the jurisdiction of national governments, with private companies often responsible for their security. In Ireland, the Department of Communications, Climate Action and Environment oversees the regulation of telecommunications infrastructure, including undersea cables. The Irish Naval Service plays a role in monitoring and protecting maritime infrastructure, including undersea cables. Internationally, the United Nations Convention on the Law of the Sea (UNCLOS) provides a framework for the laying and maintenance of submarine cables, recognizing the "freedom of the seas" and the rights of coastal states.

Conclusion:
Undersea cables are indispensable to Ireland's connectivity and economic infrastructure. Given their strategic importance, ongoing efforts are necessary to ensure their protection and resilience against potential threats. This includes enhancing security measures, international cooperation, and adherence to regulatory frameworks to safeguard these critical assets.