The range consists of three major massifs separated by fast-flowing rivers: Central (also known as Urrieles), Eastern (Ándara) and Western (also known as the Picos de Cornión). The Central and Western massifs are separated by the 1.5 kilometres deep Cares Gorge (Garganta del Cares), with the village of Caín at its head. Some of the water in the Cares river is diverted through a hydroelectric scheme, with a canal running in the northern wall of the gorge to Camarmeña. An access path next to the canal provides a spectacular walk.

Almost all of the rock in the Picos is limestone, and glacial action has contributed to create an impressive area of alpine karst. The highest peak is Torre de Cerredo, with an altitude of 2,650 metres . Many other peaks reach altitudes of over 2,600 m.