The approach is the same for Ruta Sur on El Pico de Orizaba. You start from either Azitzintla (through Texmalaquilla) or from El Ciudad Serdan and either arrange for transportation or rent a 4x4 to head up the extremely rugged road to the south side of Orizaba. The road is full of pot holes and in places the scree provides very little traction.
From Mexico City the drive takes around 4 hours and from Puebla it should take no longer than 2 hours.
If driving you can either look for a firm, flat place to park near the saddle (also known as el valle del encuentro) or drive up to the parking area (around 4300m) for Ruta Sur and hike the 45 minutes or so back to southern tip of Sierra Negra’s eastern side.
The route starts at the North-eastern base of the mountain 9the side that is further away from Orizaba) and climbs steadily through the sparsely treed slopes up onto the loose scree that one becomes accustomed to if they frequently climb in Mexico, like all of the bigger peaks in Central Mexico Sierra Negra is heavily weathered. The route upwards through the trees and for the majority of the climb you stay on the NE corner of the mountain constantly able to look back at Orizaba over your shoulder. The climb roundtrip should take from 3-5 hours and has an overall elevation gain of around 600meters or 2000 feet.
**Remember to start early to avoid the storms or banks of clouds that frequently roll in off the Gulf in the afternoon.
The most important thing that you should remember to bring is water as there are no reliable water sources found anywhere on or near the mountain. You should have 4 litres per day (around a gallon) as a general rule and it would be smart to have some Gatorade along as well. All weather gear is essential… even though the temperature seldom drops below -10 degrees celsius, it is a heat sapping cold that should be taken seriously. It is also not uncommon to encounter snow or sleet on the mountain, so for that reason alone all weather gear is important. Also trekking poles or an alpenstock (for the ascent and descent), a helmet and sunscreen would be useful so should be included as well.
*Also if making an alpine start be sure to bring along a headlamp
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