Chachani, Stratovolcano in Arequipa Department, Peru.

Chachani is a dormant volcanic complex of lava domes and cones rising 6,057 metres, 22 kilometres northwest of Arequipa. Its slopes are steep, with zigzag paths on the southeast flank, and its summit holds snowfields but no glaciers. The massif is about 17 kilometres wide and 2 kilometres high above the surrounding terrain.

Chachani is a volcanic complex whose main edifice grew inside a caldera until about 56,500 years ago, after earlier Pliocene and early Pleistocene eruptions produced the La Joya, Arequipa Airport and Yura Tuff ignimbrites. No eruption has occurred in historical times, but INGEMMET still classes the volcano as dormant and high-risk because of its proximity to Arequipa. Five glacial stages left moraines at 3,150–3,600 m and at 5,100–5,300 m, and the last glacier remnants disappeared in 2008.

The name Chachani comes from Aymara and means "brave"; alternative spellings Cacheni and Charchani also appear in documents. The complex includes named peaks such as Nocarane, La Horqueta, Los Ángeles and Trigo, and many of its edifices show yellow-orange colours from erosion and hydrothermal alteration.

Access is usually by 4x4 from the main road near Pampas Cañahuas to the north face, where the base camp sits at about 5,200 m. Acclimatize in Arequipa or the valley first, since altitude is the main obstacle. The zigzag paths on the southeast flank show how steep the slopes are. Start early enough to reach the summit at dawn, when the Pacific coast can sometimes be seen on the horizon.

Chachani is much wider than it is tall: the complex rises about 2,000 metres above the surrounding terrain but spans roughly 17 kilometres, and it is made up of more than 12 edifices, including the lava domes of Nocarane and the Airport Domes. Many of these show yellow-orange colours from erosion and hydrothermal alteration.