The Maritime Safety Directorate comprises of two main sections: the Maritime Safety Policy Division (MSPD) and the Marine Survey Office (MSO), which includes the Marine Radio Affairs Unit (MRAU). The Mercantile Marine Office (MMO) also works to the Directorate.
The Maritime Safety Policy Division is responsible for maritime safety policy, security policy and legislation (including leisure safety), aids to navigation and corporate governance of the Commissioners of Irish Lights.
The Marine Survey Office deals with the inspection, survey, certification and licensing of vessels and vessels' radio equipment; the examination and certification of seafarers' competencies; enforcement of standards by way of audits on organisations and facilities and prosecutions for breaches of regulations.
The Mercantile Marine Office maintains the Register of Shipping and the Register of Seafarers.