Parque Nacional las Cavernas del Río Camuy (Camuy River Cave Park)

The Río Camuy is the third-largest underground river in the world, and it carved this place without anyone's permission. The cave system spans the municipalities of Camuy, Hatillo, and Lares in northwestern Puerto Rico — over 220 caves mapped, more than 10 miles of caverns documented, and experts believe that accounts for only a fraction of what's down there. The main chamber of Cueva Clara runs 700 feet long and rises 215 feet high. Hurricane Maria closed the park in 2017; it didn't reopen until March 24, 2021.