[2] The NSR was established on 1 October 2005 to replace and reorganise the previous naval reserve organisation, An Slua Muirí, which in turn replaced the fore-runner Maritime Inscription founded in 1940 to act as a Port Control authority during The Emergency (WWII).

[1] The reserve supplements the crew of vessels of the Irish Naval Service during patrols of territorial waters and overseas visits, as well as conducting stand-alone operations within their respective ports, such as security duties, sighting reports and intelligence gathering.

Enlistment is open to EU citizens between the ages of 18 and 35, provided they are ordinarily resident in Ireland, can pass fitness tests, an interview, medical examination, are of good character and obtain a security clearance, and also to non-EU citizens who have been continuously legally resident in the Republic for at least three years.

The NSR is a part-time voluntary organisation, and trains members in aspects of nautical and military disciplines to supplement and aid the permanent Naval Service.

Reservists are liable to be called up on permanent service by ministerial order in times of emergency.