A local told us the story of the bolder with the hieroglyphics on it. It would be nice if they had a pamphlet with the story written on it. They don't charge $1 to get in anymore. I think it was $5. It's a short walk to the bolder and a little further up is the waterfall.
Just beautiful and...
Our guide told us the ancient drawings are pre Columbian. the glyphs were very interesting and we marveled at what they could possibly mean? To see the glyphs is a short walk from the parking lot and a few bucks to get in. If you're in the area it is worth checking out.
This trip is basically a fee based walk up a trail in the woods to see some ancient markings on a rock. History buffs will enjoy the story behind the markings, but regular people will most likely see it as some version of graffiti rather than hieroglyphic in nature.
There is only one area of petroglyphs so not really worth the effort for the petroglyphs, but it's inside the park that leads to the India Dormida and the park is worth the trip. Trails are steep, but explore beyond the Piedras Pintadas.