The Devils Glen is a nice easy walk about 1 hour outside of Dublin. Park in the carpark highlighted below and follow the trail through the woods to the waterfall. Keep an eye out of the sculptures and quotes along the trail. In the early 19th century, before the Vartry Reservoir was built in the mountains above, the river came through the glen in full uninhibited majesty, its roaring in throes of flood so loud that locals said the Evil One was howling for sinners down there. 
A collection of walks and hikes in Ireland
