Deep lock

The building of the Shannon hydroelectric scheme in the late 1920s required navigation to be maintained down to Limerick after the Parteen Weir cut off the old route via O'Briensbridge. This was achieved by building a double staircase lock at the Ardnacrusha power station. Taken from the top level this shows the lower lock which has a fall of 34ft whilst the top lock has a fall of 68ft. This is the deepest lock in Britain and Ireland.