The Cañón del Sumidero, a canyon north of Chiapa de Corzo, came into being about 36 million years ago, carved out by the Río Grijalva, which flows north along the canyon's floor. The fissure, which meanders for some 23 km (14 miles), is perhaps the most interesting landscape in the region.
You can admire the Cañón del Sumidero from above, as there are five lookout points along the highway. But the best way to see it is from one of the dozens of boats that travel to the canyon from the Embarcadero in Chiapa de Corzo (two blocks south of the main square) between 8 and 4 daily. Two-hour rides cost about $15 per person, and for about $30 you can spend the day in the ecopark of the canyon. From the boat you can admire the nearly vertical walls that rise 3,500 feet at their highest point. As you coast along, consider the fate of the Chiapa people who reputedly jumped into the canyon rather than face slavery at the hands of the Spaniards during the 16th century. Tour operators in Tuxtla Gutiérrez, San Cristóbal de las Casas, Palenque, and even as far away as Villahermosa offer excursions here.