Sitting on a 268-acre land area are the magnificent and mysterious Rio Camuy Caves. While the caves have only been discovered more than fifty years ago, these limestone formations have actually been in existence for so many centuries and are believed to have been used by indigenous Puerto Ricans as shelter. Today, the Rio Camuy Caves are the third largest cave system in the world and is one of the top natural attractions in Puerto Rico. Home to approximately half a million bats with more than half a million in number; along with some fishes and plants, the Rio Camuy Caves serve as sound habitat to local wildlife. The caves have sixteen discovered entrances with grand stalactites and stalagmites formations. One of these entrances leads to Cueva Clara which runs more 200 meters in length. Guests typically begin with audio tour and are then ushered inside the caves riding a tram. Rio Camuy Caves are open from Wednesday to Sunday except for major holidays, from 8:30am to 5pm.