[7] Since the 1970s a major role of the Naval Service has been the provision of fisheries protection in Ireland's exclusive economic zone (EEZ).

This mission entitled "EU Navfor Med" is the first time Ireland has taken part in a multi-role and multi-national naval operation.

Muirchú, formerly the British armed steam yacht Helga,[16] which had been used by the Royal Navy to shell Dublin during the 1916 rising, was the only CMS ship during this period.

Muirchu was re-armed in 1936 and purchased by the Irish government on advice of members of the later named Maritime Institute of Ireland for fisheries protection.

In 1938, the United Kingdom handed over the three treaty ports (Cork Harbour, Bere Haven and Lough Swilly).

During the war the service protected fisheries, regulated merchant ships, and laid mines off Cork and Waterford.

In June 1940, an Irish Marine and Coastwatching Service MTB returned to Haulbowline after making two trips to rescue British and French soldiers during the Dunkirk evacuation.

The subsequent strain put on the Naval Service prompted funding from the European Economic Community to acquire five additional vessels, four of which were eventually built.

Meanwhile, the former Irish lights vessel Isolda was purchased to act as a training ship, bearing the pennant number A15 and renamed LÉ Setanta (A15).

A Danish stern trawler Helen Basse was also leased for a year, serving under the name LÉ Ferdia, pennant number A16.

In 2006 LÉ Eithne travelled to Argentina, attending ceremonies connected with the 149th anniversary of the death of Irish-born Admiral William Brown, founder of the Argentine Navy, and also visited ports in Uruguay and Brazil.

They are armed with an OTO Melara 76 mm/62, and have a longer deck area that can accommodate deep-sea search-and-rescue submarines and unmanned aircraft.

[26] In May 2015, it was announced that the Naval Service would deploy a ship to the Mediterranean to form part of the EU humanitarian response to the European migrant crisis.

[27] The fleet flagship, Eithne, left Cork on 16 May 2015 for an eight-week deployment to the region, during which time the ship picked up a total of 3,377 people in the waters between Libya and Sicily.

[33] The growing "manpower crises" in the Naval Service meant that two additional ships (James Joyce, George Bernard Shaw) were placed into reserve in August 2023.

Naval Support Command oversees the personnel, logistical and technical resources of the NS, allowing the service to meet its operational and training commitments.

Ship procurement, maintenance, repair, provisions, ordnance, food, fuel, personnel and transportation are handled by Naval Support Command.

The Naval Service Diving Section (NSDS) (Irish: Rannóg Tumadóireachta na Seirbháse Cabhlaigh), formally part of NOC's shore operations section, is a specialist unit of the Irish Naval Service, a branch of the Defence Forces, the military of Ireland.

[citation needed] The Naval Service's non-military capabilities in aid to the civil power and other government departments is fishery protection, search and rescue, drugs interdiction and dive support.

This was increased to 200 nautical miles (370 km; 230 mi) again in 1994 when the introduction of the exclusive economic zone (EEZ) gave approval to the 1982 United Nations Convention on the Law of the Sea (UNCLOS).

[citation needed] Part VI of UNCLOS concerns a coastal state's continental shelf out to 350 nautical miles (650 km; 400 mi) from the coastline.

In 2007, Ireland became the first country to gain approval for the extension of its continental shelf, to the west of the island, and now has responsibility for an area of some 141,000 square nautical miles (480,000 km2; 187,000 sq mi) – an increase of 100 per cent.

[44] In its previous stance the Irish Navy was limited in its remit and sourcing of intelligence due to its lack of participation in EU Navfor Med.

There was also a lack of force protection in the event of an attack on Irish vessels but this changed with the go-ahead for EU participation.

[59] As well as the acquired and ordered OPVs, the whitepaper covered a multi-role vessel (MRV) – which would be potentially enabled for helicopter operations and have a freight carrying capacity – to replace the flagship LÉ Eithne.

[61] In August 2021, the Irish Examiner reported that the DoD was considering acquiring two former RNZN Lake-class inshore patrol vessels.

These vessels would be based on the east coast and operate mainly in the Irish Sea with the primary role of fisheries protection in light of Brexit.

[68] Non-military training takes place alongside Mercantile Marine personnel at the National Maritime College of Ireland in Ringaskiddy, near to the Haulbowline base.