Grutas de la Estrella Tonatico, Natural cave system in Tonatico, Mexico.

Grutas de la Estrella Tonatico is a limestone cave system in the state of Guerrero, about 90 km southwest of Mexico City and 11.7 km from Ixtapan de la Sal, at an elevation of 1,581 metres. Its chambers hold stalactites and stalagmites formed by water dissolving and redepositing the rock, with passages running roughly one kilometre underground.

The cave system was officially documented in 1934, though the rock formations inside formed over roughly half a million years. Water continuously shaped the limestone through dissolution and mineral buildup, creating the complex network we see today.

Local guides point out rock formations named after things they resemble, like a mammoth, a lion, a gorilla, and a chess set. These names help visitors recognize shapes in the mineral structures as they walk through the chambers.

The cave sits at 1,581 metres above sea level in the Guerrero municipality of Tonatico, about 90 km southwest of Mexico City and 11.7 km north of Ixtapan de la Sal. The descent uses roughly 450 steps fitted with walkways, bridges and lighting. The surrounding terrain is mountainous, with a peak rising to 1,767 metres about 1.1 km to the east.

From February through June, visitors can rappel down about 30 meters to reach an underground river flowing inside the cave system. This optional adventure lets people experience the cave at a deeper level for those seeking more excitement.