The River Boyne (Abhainn na Bóinne) is a river in Leinster, Ireland, the course of which is about 112 kilometres (70 miles) long. It rises at Trinity Well, Newbury Hall, near Carbury, County Kildare, and flows towards the Northeast through County Meath to reach the Irish Sea outside Drogheda. Salmon and trout can be caught in the river, which is surrounded by the Boyne Valley. It is crossed just west of Drogheda by the Boyne River Bridge that carries the M1 motorway and by the Boyne Viaduct that carries the Dublin-Belfast railway line to the east.
Despite its short course, the Boyne has historical, archaeological and mythical connotations. It passes near the ancient city of Trim, Trim Castle, the Hill of Tara (the ancient capital of the High King of Ireland), Navan, the Hill of Slane, Brú na Bóinne (an archaeological site), Mellifont Abbey, and the medieval city of Drogheda. In the Boyne Valley can also be found other historical and archaeological monuments, like Loughcrew, Kells, Celtic crosses, castles, and more. The Battle of the Boyne, a major battle in Irish history, took place along the Boyne near Drogheda in 1690 during the Williamite war in Ireland.
This river has been known since ancient times. The Greek geographer Ptolemy drew a map of Ireland in the 2nd century which included the Boyne, which he called Bubinda, and somewhat later Giraldus Cambrensis called it Boandus. In Irish mythology it is said that the river was created by the goddess Boann ('queen' or 'goddess'), according to F. Dinneen, lexicographer of the Irish Gaelic language, and Boyne is an anglicised form of the name. In other legends, it was in this river where Fionn mac Cumhail captured Fiontán, the Salmon of Knowledge.
The Boyne Navigation is a series of canals running roughly parallel to the main river from near Oldbridge to Navan. Owned by An Taisce and currently derelict, the Inland Waterways Association of Ireland are restoring the navigation to navigable status.
There are a number of railway bridges and viaducts crossing the Boyne which are well known.