The Irish galley was a vessel in use in the West of Ireland down to the seventeenth century, and was propelled both by oars and sail. In fundamental respects it resembled the Scottish galley or bìrlinn, their mutual ancestor being the Viking longship. Both the Irish and Scottish versions were colloquially known as "longa fada" (longships). The Irish galley was commonly an eight or twelve-oared vessel and was used for both warfare and trade. It was notable for its speed when rowed.

Conventional galleys were being built in a number of Irish ports in the fourteenth century, and were even commissioned by the English Crown. The use of such oared vessels in Northern Europe, in contrast to the Mediterranean, had greatly declined by the sixteenth century; their survival in the west of Ireland, as in the Scottish Isles, was facilitated by very local conditions, among them the ready availability of bays and islands.

No archeological remains have been found which would enable a detailed reconstruction of the Irish galley. There are, however, illustrations on Irish maps of the Elizabethan period and these are supplemented by written accounts. There is also a carving in the old Cistercian monastery on Clare Island (Oileán Chliara), home of the seafaring O'Malleys. The carving, though very simple, shows a vessel remarkably similar to images of its Scottish equivalent, being an oared, single-masted ship with a yard for a single square sail.

Cartographic images of the later sixteenth century, however, show interesting differences from the vessel shown in the carving. This may reflect foreign influences, since Irish galleys traded to Spain and Portugal.

Some of the most pleasing and detailed images of the Irish galley are to be found in a map of east Ulster made around 1602. It is a map by Richard Bartlett or a copy thereof. The ships depicted have a long hull, a high transom and a rudder. They have a long projecting prow, with a fairly sizable cabin on the poop. Each ship has one mast, each with a crow's nest, and a triangular sail resembling a lugsail. The rigging, with its stays, shrouds, sheets and tacks, braces, lifts and blocks, is unremarkable. The oars are prominent, with roughly ten per side, and forming a single bank along a great part of the hull. The vessels resemble those described by English mariners of the time, and are crowded with men.

Two maps of Ulster made by the Elizabethan cartographer Francis Jobson around 1590 show vessels similar to that described above, together with conventional English sailing ships. On one of these maps ("ploated for her Ma[jesty] in anno 1590") two galleys are shown, one in the northwest, the other in the northeast. Each has eight oars, and both resemble Bartlett's images (though in a somewhat simplified form) with regard to the hull and the rigging. The first galley has two masts, one a main-mast with a vertically striped square sail and crow's-nest, the other a foremast with a triangular sail. The second galley has a single mast with what appears to be a lugsail. The second map shows three more oared and sail-carrying vessels of a very similar type and appearance.

A third map of Ulster by Jobson, dated 1598, shows three galleys, each with eight oars and two with a foremast carrying a sloping spar. A third carries a topsail on the main-mast. As with the vessels described above, the forestay descends to a beak, with a cabin aft.

The depiction of these galleys matches in terms of detail the conventional sailing vessels that are also shown. Galleys were hardly used in the Elizabethan navy, and it is not likely, therefore, that the galleys shown are of English provenance.