River Caving at Arenales Charco Azul & Cueva del Indio — Puerto Rico River-Cave Adventure

You step off the van into a pocket of cool air and the steady hiss of moving water — the kind of sound that draws you down a slope without asking. Towering limestone walls fold overhead, and the Indio River cuts a bright, turquoise thread through ferns and broad-leafed plants. Guides from a certified local team check life jackets, hand out helmets, and talk through signals; then the group slips into the river and the day tightens into focus: swim, climb, float, and pass through a tunnel whose rock formations have been worked by water for millennia.