RM, rm, or R&M may refer to:
RMS Lusitania was a British ocean liner that a German submarine sank in World War I, causing a major diplomatic uproar.
RMS Queen Mary 2 (also referred to as the QM2) is a transatlantic ocean liner. She is the only major ocean liner built for Cunard Line since Queen Elizabeth 2 in 1969, the vessel she succeeded as flagship of the Cunard Line.
RMS Queen Mary is a retired ocean liner that sailed primarily on the North Atlantic Ocean from 1936 to 1967 for the Cunard Line (known as Cunard-White Star Line when the vessel entered service).
RMS Empress of Ireland was an ocean liner that sank in the Saint Lawrence River following a collision in thick fog with the Norwegian collier SS Storstad in the early hours of 29 May 1914. Of the 1,477 people on board, 1,012 died.