Grutas de Cacahuamilpa

Grutas de Cacahuamilpa National Park is one of Mexico's most spectacular natural attractions, protecting the Cacahuamilpa Caverns, one of the largest cave systems in the world. Located in the state of Guerrero near the border with Morelos, the park covers approximately 1,600 hectares of karst topography including the extraordinary cave network with chambers reaching up to 81 meters in height. ^[1] The park was established on April 23, 1936, and draws hundreds of thousands of visitors annually to witness its extraordinary formations of stalactites, stalagmites, and crystalline columns. In addition to the spectacular caves, the park encompasses the scenic gorge of the Dos Ríos (San Jerónimo and Chontalcoatlán rivers), which flow through the park and enter the cavern system underground. The name Cacahuamilpa derives from Náhuatl, combining words meaning cacao (or peanut) and agricultural field (milpa), referring to the fertile lands surrounding the cave entrance.

The cave environment of Grutas de Cacahuamilpa supports specialized cave-adapted fauna. Several species of bats roost in large colonies in the darker, undisturbed portions of the cave system. ^[1] Cave invertebrates including cave crickets, spiders, and various other arthropods complete the cave food web. The rivers flowing through the park support freshwater fish, crayfish, and aquatic invertebrates in the sunlit surface sections. The surrounding tropical dry forest harbors white-tailed deer, coatis, ocelots, various lizard species, and rich birdlife including parrots, motmots, and numerous songbirds.

The surface vegetation of Grutas de Cacahuamilpa is tropical dry forest adapted to the seasonal semi-arid climate of the region. Characteristic tree species include copal (Bursera spp.), pochote (Ceiba parvifolia), and various leguminous trees. ^[1] The dramatic gorge of the Dos Ríos rivers supports a ribbon of riparian vegetation including figs, willows, and various moisture-loving plants that contrast with the dry forest on the slopes above. Cacti, agaves, and thorny shrubs are abundant on rocky slopes and cliff faces throughout the park. Epiphytic plants cling to trees and rock surfaces in the more humid microhabitats near the rivers.

The Grutas de Cacahuamilpa cave system was formed in Cretaceous limestone by the process of karst dissolution, in which slightly acidic groundwater slowly dissolved the soluble limestone over millions of years, creating the vast chambers and galleries of the present cavern. ^[1] The active speleothem formations (stalactites, stalagmites, columns, flowstones) continue to grow as mineral-laden water drips through the cave ceiling and walls. The tourist route passes through approximately 2 km of a level passage averaging around 40 meters in width, with chamber heights varying from 20 to 81 meters; the total cave system extends approximately 10 km. ^[2] The surrounding landscape displays classic karst features including sinkholes, disappearing streams, and springs where groundwater resurfaces.

The interior of the caves maintains a remarkably constant temperature year-round, typically around 19–21°C, regardless of surface conditions, with humidity close to 100%. ^[1] The surface environment of the park experiences a warm, semi-arid tropical climate with a dry season from November to May and a wet season from June to October. During heavy rains, the underground rivers within the cave system rise dramatically and the cave can flood, leading to temporary closures for visitor safety. Surface temperatures regularly exceed 35°C in summer, making the cool cave interior particularly attractive to visitors.

The Cacahuamilpa caves were known to indigenous peoples long before Spanish colonization, and archaeological evidence including pottery fragments suggests ritual use of the cave interior by pre-Columbian cultures. ^[1] The name Cacahuamilpa derives from Náhuatl and refers to fields of cacao or peanut plants in the fertile agricultural areas surrounding the cave entrance. During the colonial period, the caves gained fame among the residents of nearby towns, and the first documented modern exploration was conducted in 1835. Nineteenth-century visitors including Emperor Maximilian and various notable figures visited the caves, which were already recognized as one of New Spain's and later Mexico's great natural wonders.

Grutas de Cacahuamilpa was declared a national park on April 23, 1936, under President Lázaro Cárdenas, in recognition of its extraordinary natural value as one of the largest cave systems in the world. ^[1] The park designation ensured that the caves would be managed as a public resource rather than exploited commercially or damaged by unregulated tourism. Electric lighting was installed in the main cave galleries to allow guided tours, and a well-developed visitor infrastructure was established over subsequent decades. The park is administered by CONANP and receives among the highest visitation numbers of any Mexican national park, with approximately 350,000 visitors annually. ^[2] Ongoing management focuses on balancing visitor access with preservation of the fragile cave ecosystem.

The guided tour of the illuminated Cacahuamilpa Caverns is the park's signature attraction, leading visitors through a series of enormous chambers filled with extraordinary speleothem formations. ^[1] Tours operate regularly throughout the day and last approximately 90–120 minutes for the main 2 km route. The outdoor amphitheater adjacent to the cave entrance hosts cultural events and concerts. The Dos Ríos gorge offers hiking along the river banks with scenic views of the limestone canyon walls. Adventure tourism including rappelling and cave exploration beyond the tourist route is available through specialized operators.

The park is located approximately 55 km from Taxco via Federal Highway 55/166, and about 150 km from Mexico City via Cuernavaca. ^[1] The park has a well-developed visitor complex at the cave entrance including ticket booths, parking, a restaurant, souvenir shops, and restrooms. ^[2] The cave tours are conducted in Spanish with fixed departure times. Admission fees are charged. Accommodation is available in the nearby town of Taxco, one of Mexico's most beautiful silver-mining towns and a Pueblo Mágico. The park is open daily year-round except when flooding forces temporary closures.

Conservation of the Cacahuamilpa cave system focuses primarily on maintaining the integrity of the cave environment and its exceptional formations. ^[1] The illumination system and visitor foot traffic create algae and microbial growth on cave surfaces, and periodic cleaning and monitoring are required. The bat colonies in the undisturbed portions of the cave are protected from disturbance, as they are crucial for cave ecosystem function and for pollination and pest control in the surrounding landscape. Groundwater quality in the karst system is monitored to detect contamination from surface agricultural or urban activities. The park's management plans aim to maintain visitor experience while minimizing physical and chemical impacts on the cave environment.