SS (RMS) Mona's Isle (IV) was a steel, triple-screw turbine driven packet steamer operated by the Isle of Man Steam Packet Company between 1920 and 1948. Built in 1905 for the South Eastern & Chatham Railway Company, she was operated as Onward between Folkestone and Boulogne. In 1918 a fire was only controlled by scuttling the vessel. She was righted and in 1920, the hull was purchased by IOMSPCo to replace tonnage lost during the war. She was the first ship to complete a round trip during the evacuation of Dunkirk (Operation Dynamo), rescuing a total of 2,634 troops.