Up the River Azul towards the mountain range, approximately at 9.5 Km. from the confluence with the Arroyo Blanco, a very unusual phenomenon can be observed: its narrowing to a space of one meter in width and forty meters in depth, for a length of approximately one kilometer.
There are programmed guided excursions, that facilitate the access to this place. There is also a shelter with lodging (sleeping bag) and meal (strong mountain dish).