This article is about the Class III road numbered C84 maintained by DfI Roads. For other roads numbered C84, see C84.
The C84 runs for over 25 kilometres and as a result, is incredibly long for a class III route. It is even longer than the A44, which it runs roughly parallel to for much of its journey. The road starts on the A44 in Ballycastle and heads south west into the countryside along the west shoulder of Knocklayd, a large 567m whaleback of a hill which stands behind Ballycastle. The road soon comes to a T junction where the short link road to the right takes traffic back onto the A44. Turning left, the road continues south and crosses the B15 at a scattered crossroads situated east of Armoy. From here the road becomes remarkably straight for several kilometres before passing the C81 at a T junction in Magherahoney. After crossing the River Bush, the latter heads off to the west and the former continues its long journey on a broadly north south alignment. Loughguile is the next sizeable place that the road comes to, where it meets the C86. Beyond here the road passes through the smaller settlement of Corkey. Soon the road meets the eastern end of the C85 at a crossroads north east of Cloughmills. Continuing on south, the road eventually ends on the B64 near Clough.