Coropuna is a long, large extinct volcanic mountain located in the Cordillera Occidental of the Andes in Southern Peru. It is situated on the high plain between Chuquibamba and Cotahuasi, in the department of Arequipa. It has six peaks shown on the map at over 6,000 meters. There are various elevations given for the summit, but the commonly accepted one is 6,425 meters (21,079 feet). It was once thought that it might be the highest mountain in the Americas, but Hiram Bingham and the members of the University of Yale archaeological expedition were disappointed to find out that it wasn't, when they climbed and measured it in 1911. You can read about their expedition here. American school teacher Annie Peck actually climbed the mountain ahead of them, earlier in the year, but according to Jill Neate in “Mountaineering In The Andes”, she climbed two lower peaks, placing a 'Votes For Women' banner on one of them. Neate gives much higher elevations than other sources, as did Bingham.
Coropuna, which Bingham says comes from the Quechua coro meaning “cut off at the top” and puna meaning “a cold, snowy height”, was a very sacred mountain to the Incas. I have read of many archaeological sites around the base of the mountain, and on the slopes of it, but have not personally seen any. Tatraman mentions some on the west rib route in one of his comments. There are pre-Inca ruins on the north side of the mountain at Macua Llacta.
From Chuquibamba the (sometimes rough) gravel road climbs up to about 13,000 feet to the high plain, where you get your first view of Coropuna, the Chila range, and if the weather is clear, Ampato. When you reach the rim of the canyon, there is a cell phone tower up above on the left. Continue straight at the junction, the small road going to the right goes to Pampacolca and around the east side of Coropuna. About an hour from Chuquibamba, the road drops down and crosses a small stream at Rata. There isn't any bridge; the road just goes through the water. This usually isn't a problem but during the rainy season the water can be up to a foot deep, however the roadbed is solid. After the stream crossing, turn to the right in front of the shell of a building (which may have people living in it).
There is a road going left that goes to Andaray. Take the right fork at the next junction; there is a sign there that shows 116 Km to Cotahuasi. Soon after this you will see some small trees, the only ones that grow on the high plain and somehow thriving in between the rocks. If they aren't covered in dust, you can see their reddish bark, something like a manzanita tree. The road continues to wind around, and up and down, as it goes around the south and west side of Coropuna. You will also be able to see Nevado Solimana off to your left around this time.
There are two small roads branching off to the left, both of which go to the village of Salamanca, in a canyon below Solimana. There are often alternate routes, some are parallel paths, and some are shortcuts, if in doubt stick with the most traveled or main road. Coropuna will continue to loom larger and closer on your right as you go around the constant curves and through the many quebradas (dry gulches or small canyons). As you get closer to the mountain, the hills will turn to many shades of red and yellow, besides the normal brown and black. About two to two and a half hours from Chuquibamba the road drops down a bit and Coropuna will not be visible. On the left will be a dilapidated building, with some of the corrugated concrete roof missing.
The climbers who take the public bus get off here. If you are driving, continue about five minutes past here. You will go around a right hand curve and be heading more towards the mountain. There will be a minor dirt road going off to the right, turn here. Immediately you will come to a fork in the road. The right fork goes down to the lake, if you want to camp there. The left fork goes to the highest base camp at 16,470 feet, which is just before the end of the road. There are less rocks here and many good tent sites, with a large boulder to shelter somewhat from the wind. There are many vicuña in the area, they are often seen around the mountain, especially in the swampy area below the lake.
The 'road' does continue for a while but it was not possible to drive much farther because of a rock-strewn gully, just a few minutes from the base camp. We hiked up the road until that turned to go around the west end of the mountain at about 17,000 feet. From there we followed a faint climber's trail towards the west rib, which is the main route to the summit. Our route took us off to the left and followed an undulating ridge, rather than going directly towards the west rib, because there is a deep gully there and the climb up out of it would have been in steep, loose sand, however this is the fastest way to come back down.
During the rainy season, from January to March, the weather is often unstable, with some sunny days but storms can roll in very quickly, and the mountain will be covered in clouds, with rain and snow. The later half of December and the first half of April can get some bad weather as well, but most of the rest of the year will usually provide sunny days and clear cold nights.
It is not a technically difficult mountain to climb, the biggest problems are penitentes that get increasing larger during the dry season. There is some crevasse danger, but they are easily avoided on the west rib route. Unless it is fresh, the snow is quite hard and icy, crampons and an ice ax are normally necessary as it is about a 45° angle if you go straight up the rib.
There usually isn't any water above Laguna Pallachocha, although in the afternoon you may be able to find a stream coming down from the glacier to the left of the summit. Often times you can hear water here even though none is readily visible.
If you start at the high base camp, the mountain can easily be climbed in two days if you are in good shape and are acclimated to the altitude. Due to the high elevation, I would recommend that you do some lower peaks first. The first time I climbed it, I did it with climbing friends from Lima. We did not do any other mountains first to prepare, it took us three days and was really hard.
Camping is permitted anywhere in the area. There are three buses that pass through during the night, so if you aren't arriving on one of them, I would recommend camping at the lake or near the end of the road at the highest base camp. On the climb, there is decent camping in a sandy bowl, just before climbing up to the west rib, and there are a couple of higher campsites in the rocks, before reaching the normal snow line.
There should be Claro cellphone reception higher on the mountain, certainly on the summit, as it is line of sight to their tower above Chuquibamba. There is no Movistar reception anywhere on the high plain between Chuquibamba and Cotahuasi, as their towers are down in the canyons.
About three hours past Coropuna, is Cotahuasi Canyon, and the village of Cotahuasi. This is a good place to spend a few days before your climb if you need to acclimatize to the altitude. There are many lower mountains, from 12,000 to 17,000 feet, enough trails to keep you busy for weeks, and plenty of natural attractions such as waterfalls, hot springs, rock and cactus forests, as well as traditional villages surrounded by terraced fields. Check out the above linked pages to find more information.
Just an hour and a half past Coropuna, is Nevado Solimana, which at 6,093 meters, is just 10 feet short of 20,000 feet. It is a harder climb technically, and is best climbed in May or June when there is more snow, which is needed for the normal route. North of Coropuna is Nevado Firura (5,498 meters - 18,038 feet), a rarely climbed mountain requiring a long approach hike, but an easy summit climb, at least when there is lots of snow.
In addition to these, there are all the mountains near Arequipa and Colca Canyon, including El Misti, Chachani, Ampato, and many others. See the links at the left, as well as the Volcanoes of Arequipa page, for more information.