Film on the role of the Royal Navy, discussing the role of the service in support of NATO and protection of British seaborne trade. The film also looks at the Navy's ships, submarines, aircraft, communications and weapon systems, including their purposes and capabilities. Modifications made as a result of lessons learned during the Falklands War are discussed and the principles of power projection through the use of maritime air power are explained. Royal Marines appear on exercise in Norway, shore repair facilities are shown and the challenges of submarine inshore operations are described. Hydrographic survey work, co-ordinated from the Hydrographic Office at Taunton, provides accurate charts, Fishery Protection vessels inspect fishing vessels and sailors train for disaster relief operations and firefighting at sea.