Shown here are all the major rivers and tributaries of Ireland with their lengths. Starting with the Northern Ireland rivers, and going in a clockwise direction, the rivers are listed in regard to their entry into the different seas: the Irish Sea, the Celtic Sea and the Atlantic Ocean. Also shown are two tables. Table 1 shows the longest rivers in Ireland with their lengths, the counties they flow through, and their catchment areas. Table 2 shows the largest rivers in Ireland in cubic metres per second.

Ireland is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the second-largest island of the British Isles, the third-largest in Europe, and the twentieth-largest in the world.