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Marine Notice: Subsea Survey for Fibre Optic Cable Off South Wexford

16th June 2025
Irish Sea Contractors Ltd working on a subsea cable project
Irish Sea Contractors Ltd will be completing a subsea survey and protection campaign of a fibre optic cable off the coast of Co Wexford over the next several months Credit: Irish Sea Contractors Ltd

The Department of Transport has been advised by Irish Sea Contractors Ltd that they are completing a subsea survey and protection campaign of a fibre optic undersea cable off the coast of Co Wexford.

All works will be completed by diving operations which are expected to take place between now and 30 October, subject to weather and operational constraints.

The survey campaign will be confined to an area located off Ballygrangan’s Beach, east of Kilmore Quay. A map and coordinates of the survey area, as well as contact details, can be found in Marine Notice No 37 of 2025 attached below.

A dive rigid inflatable boat (RIB) and a safety boat will be used on the survey section of the project. The dive RIB is the ISC1 Redbay (callsign EIA2737).

During diving operations, the vessel will display a dive flag. As the dive vessel will be restricted in its ability to manoeuvre when the diver is in the water, all other vessels operating within this area are requested to keep their distance and pass at minimum speed. The vessel will monitor VHF Channel 16 at all times.

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Published in Undersea Cables, Diving
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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.