The Blackwater is aptly named. Called in Irish An Abhainn Mhór (The Great River) it is the second longest waterway in Ireland, exceeded only by the Shannon. Rising in County Kerry’s Mullaghareirk Mountains, the Blackwater flows for more than 100 miles to drain into the sea at Youghal, County Cork. Here outside Cappoquin, County Waterford, the river turns abruptly south, grows broad and tidal, and is thereafter largely bordered by ancient woodland.