Sumidero Canyon

The Sumidero is Chiapas compressed into one gorge: the Grijalva river slides between vertical walls that rise as high as 1,000 metres, and the standard approach - a fast open boat from the colonial river town of Chiapa de Corzo - runs the narrow 13-kilometre passage beneath them. The scale only lands from the water: cliffs stacked in bands of jungle and bare rock, vultures riding the updrafts, crocodiles hauled out on the banks and spider monkeys in the gallery forest. The celebrated Christmas Tree formation drips down one wall, a tiered cone of moss and travertine fed by a seasonal waterfall, greenest after the rains. The run ends near the Chicoasen dam, whose reservoir tamed the river; separate road-accessible miradores along the rim above Tuxtla Gutierrez give the top-down counterpart. The canyon is emblem enough to appear on the Chiapas coat of arms.

What you actually see

• The kilometre walls - vertical rock closing over the river passage.
• The Christmas Tree - the tiered moss-and-travertine cone on the cliff.
• The wildlife banks - crocodiles, monkeys and soaring vultures.
• The rim miradores - the top-down panoramas from the Tuxtla road.

When to go

November to May for dry, clear boat days; the Christmas Tree flows fullest just after the rains in late autumn. Morning departures beat both heat and afternoon wind chop.

Honest expectations

The boats are fast and loud - hats fly and the midday sun off the water is brutal, so bring sun cover you can hold onto. After heavy rains the river can carry floating debris, which dismays some visitors. The rim viewpoints need a separate half-day by road; the boat alone misses the top-down drama.

Nearby

Chiapa de Corzo's arcaded plaza, Tuxtla Gutierrez and the highland town of San Cristobal de las Casas.