San Juan de Dios de Cárdenas, or simply Cárdenas, is a municipality and city in the Matanzas Province of Cuba, about 116 km by air east of H…San Juan de Dios de Cárdenas, or simply Cárdenas, is a municipality and city in the Matanzas Province of Cuba, about 116 km by air east of Havana. Cárdenas is the 15th most-populated Cuban city and the second most populated one not being a provincial seat, after Manzanillo.