File:Dún Laoghaire-Rathdown COA.svg
Per chevron argent and vert, in chief an ancient Irish crown proper between in the dexter a slip of oak of the second fructed of the third and in the sinister a trefoil slipped also of the second, in base on waves of four of the first and azure a Viking longship sail set oars in action, also proper.
Motto: Ó Chuan go Sliabh.