The Koralpe, also referred to as Koralm, is a mountain range in southern Austria which separates eastern Carinthia from southern Styria. Running from north to south, it drains to the river Lavant in the west, and to the river Sulm in the east. Its highest elevation (2,140 meters) is the Große Speikkogel, a popular hiking destination and also a node for military radar airspace surveillance.