The Cardó Massif (Catalan: Massís de Cardó, IPA: [məˈsiz ðə kəɾˈðo]; Spanish: Macizo de Cardó), also known as Cardó-Boix Massif, is a mountain massif in the Baix Ebre comarca, in Catalonia, Spain. This massif is composed of a number of mountain ranges located on the left side of the Ebro river near Tortosa. The massive calcareous cliffs of the Serra de Cardó form the eastern side of the spectacular gorges through which the Ebro River winds its way in the final stage of its course, separating the Ebro Valley from the Mediterranean coastal area.