Grutas de Cacahuamilpa

The caves have a long Indigenous history and several names; the best known is Salachi. The modern name comes from a nearby settlement and means peanut field in Nahuatl.

Their wider fame is usually traced to 1834, when a man named Manuel Sainz de la Pena is said to have hidden inside while fleeing the authorities. Scientific visits followed, the caves opened to the public in the 1920s, and in 1936 the government declared the site a national park.

This is a karst cave system, hollowed out of limestone by slowly moving water over a very long span of time. The result is a chain of about ninety large chambers, locally called salons, linked along a passage that runs for kilometers. Roughly twenty of them are lit and open to visitors.

The rooms are big. Many average around forty meters wide, and ceilings reach from about twenty meters up to some eighty meters overhead. Stalactites and stalagmites, columns, and flowstone cover the walls, shapes that guides have long given names.

Two rivers, the San Jeronimo and the Chontalcoatlan, run underground through the park and meet nearby to form the Amacuzac River.

In pre-Hispanic times the Chontal people held ceremonies and rites inside the caves. Excavations have turned up fragments of pre-Columbian pottery, physical evidence that people used the interior.

Across Mesoamerica, caves were understood as thresholds: openings into the earth and the underworld, tied to water, rain, and the origins of people. That worldview helps explain why a cavern of this scale would have been treated as a charged, sacred place, though the specifics of what was done here are only partly known.

Visitors go in on a guided tour along a paved, lit walkway that runs about two kilometers into the hill and back. The air stays cool and damp, and the lighting picks out the larger formations.

One chamber, called the Auditorium, is used for concerts, most often symphonic music, and sometimes hosts performances tied to Taxco's yearly Jornadas Alarconianas. The caves draw on the order of 350,000 visitors a year.

The caves sit inside a national park of about 1,600 hectares that straddles the border of Guerrero and Morelos. Above and around the entrance are the two river canyons, a small botanical garden, and marked climbing routes on the cliffs.

The setting near Taxco, a colonial silver town, makes the park an easy day trip and one of the better known natural sites in this part of central Mexico.