In Cuevas del Indios (Indian Caves), once you've climbed down the cliff side into the rock crevice (it sounds much more daring than it is, I promise), you'll find a ladder that leads to the Taino Indian petroglyphs.
I was surprised at the quality of the preservation of these ancient drawings. This cave is protected from the elements, with only ocean mist and the occasional large surge of water from a massive wave crashing against the cliffs outside. In this image, I stand at the top of a tunnel and look back into the main cavern of the cave. You can see a detailed petroglyph on the left side of the tunnel.
If you are looking for an outdoor adventure that involves a glimpse into a lost culture and people of Puerto Rico, this is the best place for you. A $2 fee gains you entrance to the self-guided tour of the caves and views of the seven cliff arches. For a donation, you can utilize a guide. The friendly staff speak Spanish and English and will gladly tell you about the motion pictures filmed at this location, as well as upcoming films.