The Royal Canal (Irish: An Chanáil Ríoga) is a canal originally built for freight and passenger transportation from the River Liffey at Dublin to the River Shannon at Cloondara in County Longford in Ireland.
Work commenced in 1790 and lasted 27 years before finally reaching the Shannon in 1817. The canal passes through Maynooth, Enfield and Mullingar and has a spur to Longford. The total length of the main navigation is 145km (90 miles), and the system has 46 locks.
There is one main feeder (from Lough Owel), which enters the canal at Mullingar. In 2006 a commemoration marker was erected at Piper's Boreen, Mullingar, to mark the 200 years since the canal reached Mullingar in 1806.
At the Dublin end, the canal once reached the Liffey through a wide sequence of dock and locks at Spencer Dock, with a final sea lock to manage access to the river and sea, but these are no longer fully operational, and access to the river is especially challenging.
The canal is notable in that the Dublin - Mullingar railway line was built alongside the canal for much of the distance. The meandering route of the canal ensures a speed limiting curvature for the railway. The canal was bought by the Midland Great Western Railway to provide a route to the West of Ireland, originally planning to close the canal and build the railway along its bed. The total cost of building the canal was £1,421,954.
The canal travels across one of the major junctions on the M50/N3 in a specially constructed channel.
Today Waterways Ireland is responsible for the canal.
The canal is currently being repaired, and it is intended to reopen it for navigation of its full length (from the Shannon Navigation to Dublin) by the middle of 2008. In early 2007, it is possible to go from Dublin to Ballymahon, and boats of up to 22.9m x 4.0m x 1.2m are allowed. Access points currently exist near Leixlip and at Maynooth, Enfield, Thomastown, Mullingar, Ballinea Bridge and Ballynacargy.
The other large canal in Ireland is the Grand Canal from Dublin's southside through the Midlands to the River Shannon.