Grutas de la Estrella

South of Tonatico, just off the federal highway to Taxco, the Grutas de la Estrella burrow into the limestone of the Cerro de la Estrella. They are part of an ecological reserve and are the best-known natural attraction in the municipality, a cooler, darker counterpart to the hot springs that bring most visitors to Tonatico and Ixtapan de la Sal.

The standard visit follows a lit path through chambers where water has built stalactites, stalagmites and flowing curtains of stone over thousands of years, with walls that take on strange shapes in the lamplight. Its waters drain toward the Chontalcoatlán and San Jerónimo rivers, which in this karst country run beneath the mountains and carved the famous Cacahuamilpa caves a short way south.

For something more active, guides offer adventure routes deeper inside, including a rappel down a roughly 15-meter drop and a walk along the underground river. In the rainy season, water pours down as a waterfall inside the system. Bring shoes with good grip, since the path is damp and has stairs, and a light jacket for the cave's steady chill.