The flyboat (also spelled fly-boat or fly boat) was a European light vessel (developed primarily as a mercantile cargo carrier, although many served as warships in an auxiliary role) of between 70 and 200 tons, used in the late 16th and early 17th century; the name was subsequently applied to a number of disparate vessels which achieved high speeds or endurance.
Richard the Lionheart developed a fleet of war galleys that was referred to as flyboats in the twelfth century. They were of Viking longship design made for speed and riverine warfare. They were tested in a port at Les Andelys under the protection of his new castle there. These boats were on the Seine River and from the towns of Portsmouth to Rouen.
The name "flyboat" is also derived from Dutch vlieboot, a boat with a shallow enough draught to be able to navigate a shallow vlie or river estuary, such as the Vlie. Armed flyboats were used by the naval forces of the Dutch rebels, the Watergeuzen, in the beginning of the Eighty Years' War. The type resembled a small carrack and had two or at most three masts, a high board and a dozen iron cannons. Small, inexpensive and manoeuvrable, it was ideal for privateering activities in the European coastal waters and soon imitated by privateers or pirates of other nations. The Dutch navy, and their enemies, the Dunkirkers, at first extensively employed flyboats. In 1588 the army of Alexander Farnese was blocked in Dunkirk by a fleet of thirty Dutch flyboats commanded by Lieutenant-Admiral Justin of Nassau, preventing him from joining the Spanish Armada to invade England.