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Marine Notice: Cable Operations for Celtic Interconnector This Week

15th May 2026
File image of the Van Oord vessel Calypso
File image of the Van Oord vessel Calypso, which is undertaking cable operations for the Celtic Interconnector Project Credit: Van Oord

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 in the Celtic Sea. Operations were set to begin on Friday 15 May and are expected to last seven days, subject to weather and operational constraints.

The activities will be conducted within the cable corridor extending +/- 1,000m either side of cable route centreline. Mariners are advised to provide a wide berth and navigate with caution in the area. Fixed fishing gear in this area is required to be removed.

Works will be undertaken by the vessel Calypso (callsign PDNV). It is requested that anybody having prior knowledge of potentially submerged or moored objects on the seabed within the area of operations which could form a hazard to the vessel/equipment should contact Van Oord.

During the cable lay operations, the work vessel will keep a listening watch on VHF Channel 16 and will actively transmit an AIS signal. A listening watch will also be maintained on VTS VHF Channels as
appropriate.

The vessel will broadcast daily, and at shorter intervals as may be required by passing traffic, the vessel position, operational information, and planned operations for the next twenty-four hours.

A map and coordinates of the work area, as well as contact details, can be found in Marine Notice No 25 of 2026 attached below.

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Published in Undersea Cables
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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.