Tolantongo Canyon, Natural canyon in Hidalgo, Mexico

Tolantongo Canyon is a gorge in Hidalgo with towering limestone walls where thermal springs emerge from caves and flow into the Tolantongo River. The site includes hotel complexes, camping grounds, dining options, and parking for visitors.

The canyon lies in the Sierra Madre Oriental, in the Carso Huasteco subprovince, where rivers tributary to the Pánuco cut through folded Mesozoic rocks. Its oldest exposed layers are Upper Cretaceous limestones interbedded with strongly folded shales, with dips often above 30° and near-vertical on the left slope; near the grotto on the right slope, limestone beds dip about 80°.

The canyon lies across the municipalities of Cardonal, Tlahuiltepa and Eloxochitlán, and the tourist caves and pools sit in Cardonal. The name Tolantongo comes from the river that carved the gorge, a tributary within the Pánuco basin. Visitors can watch the water emerge at the caves and follow the streambed downstream.

The canyon runs west to east from about 2,300 m above sea level northwest of Cardonal down to roughly 1,150 m near the village of Itztacapa, so the descent is steady and the lower eastern section is the warmest. The cave area sits on the right-hand slope, where limestone beds dip at 80 degrees. Alluvial deposits are nearly absent near the caves because the steep riverbed keeps sediments moving.

The thermal pools maintain a steady temperature around 38°C (100°F) year-round due to volcanic activity beneath the limestone. This natural heating system makes the canyon a rare geological occurrence.