The entrance to this long cavern is situated in pine woods 9km southeast of San Cristóbal, a five-minute walk south of the Pan-American Hwy. The first 350m or so of the cave is lit and open for viewing, with a concrete walkway threading through a dazzling chasm of stalagmites and stalactites. Beyond that you have the option of continuing (extra M$30) in total darkness with just a flashlight (provided) for company for another few hundred meters.
Horseback riding is available from the parking area, where you’ll also find comedores (food stalls).
To get here, take a Teopisca-bound combi (M$20) from the Pan-American Hwy, about 150m southeast of the OCC bus station in San Cristóbal, and ask for ‘Las Grutas.’