The Cordillera Huayhuash is a mountain range in the Andes of Peru. Aligned north to south, the main range of some twenty peaks stretches for approximately 25 km, with a subsidiary range of smaller peaks stretching out to the west for approximately 15 km. Six of the peaks exceed 6000 m. Included among them are Yerupaja (6617 m), the second highest mountain in Peru (behind Huascarán at 6768 m), and Siula Grande (6344 m), made famous by Joe Simpson in Touching the Void.
There are many lesser peaks surrounding those covered by ice, and several passes exceeding 5000 m. It is necessary to travel a considerable distance from the central range to find ground lower than 3000 m, even on valley floors, and the Cordillera Huayhuash is often taken to include this much larger area.
The area is barely populated at all, with what hamlets there are being very small and generally only found below 4000 m (the snowline is found at approximately 4800 m). The nearest villages are Chiquián (3400 m) and Cajatambo (3375 m). Some mining takes place in the area, so to the north of the mountains there is an unsurfaced road leading up to as high as 4750 m. In 2002 the Peruvian Ministry of Agriculture declared the Huayhuash a "reserved zone" and prohibited certain economic activities, including any future mining.
The range has become noted for trekking in the form of the Huayhuash Circuit, which is considered quite a challenge and is undoubtedly far more demanding than the famous Inca Trail in the south of Peru. Fewer people trek the Huayhuash than the nearby Cordillera Blanca. The circuit generally takes between ten and fourteen days, depending on the route taken.
Most of the walking, and most of the campsites, are above the 4000 m treeline, so the landscape appears rugged and mountainous, affording views over very wide areas. The area is noted for its spectacular glacial lakes. Hot springs can also be found in the area. Condors, llamas, alpacas and viscachas can be seen. Trekking is almost always undertaken in the dry winter months of May to September, and the large town of Huaraz over 100 km away is the usual choice for a base, with Chiquián acting as the "Gateway to the Huayhuash". It is possible to penetrate into the mountains as far as the village of Llamac (3300 m), reached by road built in the late 1990s.