Cañón de las Mariposas is a slot located is Southeast Mexico near Jalcomulco in the Veracruz region and is on the east side of Cofre de Perote, a huge but extinct volcano. It is named for the Morpho butterflies that gather there.
It was a neat canyon with some good narrows, crystal clear water, several jumps, and flow-stone and stalactites on a lot of the walls. There were no rappels, but several jumps and downclimbs. Jalcomulco is a hot place, so the water was really refreshing.