Grutas de Tolantongo

Geothermal water emerges high in a canyon in Hidalgo and has been channelled into dozens of small pools stacked in terraces down a cliff face, so you sit in warm turquoise water looking straight out over a gorge. The river below runs warm enough to swim in all year and is an unlikely milky blue from dissolved minerals. Above it a cave and a tunnel take you inside the rock, where hot water pours from the ceiling and walls in a natural shower. The whole complex is owned and run collectively by the local ejido rather than a company, with the income going to the community, which is why it has grown steadily without ever quite becoming a resort.

What you actually see

• The cliff pools - terraced turquoise pools stacked down the canyon wall.
• The cave and tunnel - hot water falling from the ceiling inside the rock.
• The warm river - milky blue and swimmable along the canyon floor.
• The zip line - crossing the gorge above the pools.

When to go

October to May avoids the summer rains that can close the canyon road and turn the river brown. Midweek is far quieter; weekends, Holy Week and Christmas are extremely crowded. Advance booking is now required and sells out well ahead for peak dates.

Honest expectations

This is enormously popular with Mexican families and at peak times the pools are shoulder to shoulder, which is a very different experience from the photographs. Booking ahead is compulsory. The access road is a long series of steep hairpins that some drivers find genuinely alarming, and the descent into the canyon is steep. Card payment is limited, so bring cash.

Nearby

Ixmiquilpan is the nearest town; Real del Monte and Pachuca are two hours southeast.