On the highway east from Chiapa de Corzo towards San Cristóbal, you catch occasional glimpses of the lower reaches of the Cañón del Sumidero. Through this spectacular cleft the Río Grijalva runs beneath cliffs that reach 1000m in height in places, the rock walls sprinkled with patches of bright green vegetation. The typical tour is on a mesmerizing boat ride down the river from Chiapa de Corzo, or you can drive along the rim from Tuxtla.
From Tuxtla, Autobús Panorámico runs a bus from the plaza along the road that borders the rim of the canyon, passing all the main miradores – the best views are from La Coyota. The buses go only when five or six people turn up. There’s no public transport to the area.
In Chiapa de Corzo, several companies offer regular boat trips down the canyon, all for the same price. The first office you reach is Turística de Grijalva (t961/600-6402), on the west side of the plaza. Or you can head straight south down the street to the embarcadero, where other companies operate. During Mexican vacation times, boats fill with the requisite ten people almost immediately, and it doesn’t matter where you buy your ticket; in slower times, it’s best to show up early and go from company to company to see which boat is closest to full. Tours last a couple of hours, snaking through the whole gorge to the Chicoasén Dam, which forms a lake at the northern end. Along the way you pass several waterfalls, including the remarkable El Árbol de Navidad, where calcareous formations covered with algae resemble a Christmas tree from a distance. Crocodiles and spider monkeys can often be spotted, as well as vast numbers of pelicans, egrets and cormorants.