Aratz (meaning 'pure' in Basque, after its stone surface devoid of vegetation) is a mountain of the Basque Country in Spain located at the mountain range Altzania (also called Urkilla) that provides the extension for the massif Aizkorri. It lies right on the line between provinces Gipuzkoa and Álava, the summit rising at 1,443 m high, next to Elurzuloak (1,431 m). The whole Aizkorri and Aratz area was declared the Aizkorri-Aratz Natural Park in 2006.