Sumidero Canyon National Park

The 1,000-metre gorge of the Rio Grijalva in Chiapas protects a canyon ecosystem of dry tropical forest, cave-nesting colonies of swifts, and riparian habitats supporting crocodiles and tapirs within the canyon depths. The canyon walls contain a Christmas Tree Cave — a section where constant seepage creates a green algae formation that resembles a decorated tree — visible from the boat tours that traverse the canyon.