About 8km southwest of Las Coloradas is this well-signposted, 2km-long trail, the park's headline nature/archaeological hike. An underground river here has created 20 large caverns, one of which contains the famous ĺdolo del Agua, carved from stalagmites by pre-Columbian Indians; there's also a 500-year-old cactus, butterflies, 170 different species of birds (including the tiny colibrí) and multiple orchids.
Guides are required but included in the entry cost. You should allow two hours for the stroll in order to take in everything. There are hundreds of flies here. Bring repellent.
The park is flecked with other trails, the best of which is the 30km trek to Alegria del Pio, replicating the journey of the 82 rebels who landed here in 1956. Due to its length and lack of suitable signage, this rarely tackled trail is best done with a guide (the trail actually runs on a further 70km into the Sierra Maestra, if you're feeling energetic). Inquire at Ecotur in Bayamo beforehand. You'll need to arrange for transport to meet you at Alegria del Pio.