An excursion into the Sierra de la Güira introduces visitors to the cool atmosphere of pine and cedar forests. An underground river (Río San Diego) cuts across Cueva de los Portales; the cave is primarily of historical interest, as it was Che Guevara's headquarters during the 1962 missile crisis. With a number of access points, it was a formidable natural fortress. Inside, Che's radio and the office where he would meet with his officers can be seen.