A short distance east of the park entrance, on the northern side of the highway, look for Las Caritas, a small rock formation with what are believed to be pre-Taíno petroglyphs. Bright-yellow handrails guide the short but somewhat tricky climb up the hillside – you’ll need shoes or decent sandals. You'll be rewarded at the top with a close look at the pictures and a fine view of the lake. Very little is known about the meaning of the figures.
Note that much of the rock here is petrified coral, a remnant of the time the entire area was under the sea.