Cerro Castillo is a jagged rocky peak located in the Aysén del General Carlos Ibáñez del Campo Region of Chile, within the Cerro Castillo National Reserve. Castillo means castle in Spanish, and the steep basalt walls of the mountain indeed make it look like one. On its sides are a few small glaciers and lakes fed by them.
The base of the mountain can be approached from the road in one day along Estero Parada river.
The route followed an 800-meter-high, snow-and-ice couloir which had an angle of 55° in the upper part of the west face of Cerro Castillo.