Acoculco

Beneath the fields of Acoculco lies volcanic heat. The village gives its name to the Acoculco caldera complex, an old volcanic system of late Pliocene to Pleistocene age on the Puebla–Hidalgo border that geologists study for its geothermal potential. Wells more than 1.5 km deep have confirmed a thermal anomaly underground, though none has yet proven a usable resource. Studies of the area measure carbon dioxide seeping from the ground and map springs and ground altered by hot water; one reference point is exploration well EAC-1. In October 2015 Mexico's Energy Secretariat gave the CFE permission to explore the area, and in 2022 the utility announced another well, EAC-3, at a cost of about 70 million pesos.

The locality appears in official records as Acoculco (Alamedilla). It had 1,993 residents in 2020 and is one of the highest settlements in the region: it sits at 2,767 m in the far north-west of the huge municipality of Chignahuapan, the second largest in Puebla at 759 km². In Nahuatl the name is read as "where the water twists", from atl, water, and cocoltic, something twisted. At that height the air is cold: the municipality ranges from mild to cool, with averages of 10 to 16 °C and 600 to 900 mm of summer rain, and its highest summit is the Peñón del Rosario at 3,440 m.

Farmland dominates the surroundings, covering more than half of Chignahuapan, alongside forest on another 37%. The municipal seat, about 22 km away, is a Pueblo Mágico known for its Christmas baubles and ornaments, clay pottery, gabanes and jorongos woven on looms, and rustic furniture. Local food includes mole poblano, pressed chicharrón and cheese bread, with sweets of candied squash and tejocote, pumpkin-seed and pine-nut jamoncillo and milk sweets. Tulancingo, across the line in Hidalgo, is about 23 km off.