Rio Camuy Cave Park

I’d read the number before we went — third-largest subterranean river in the world — and I still didn’t believe it until I was standing at the edge of it, in the dark, listening to the Rio Camuy move through rock it’s been carving for a million years. Lia grabbed my arm on the tram ride down into the sinkhole, half laughing, half not, because the trees just fall away and you’re descending into something that swallows the municipalities of Camuy, Hatillo and Lares whole. It opened to the public in 1986, after decades of speleologists mapping passages nobody outside Puerto Rico had really heard of, and walking in you can feel that slow, careful history — this wasn’t a tourist trap built overnight, it was earned.

Cueva Clara is the chamber that gets you. I’d been in caves before — small ones, the kind where you duck and shuffle — but nothing prepared me for a ceiling so high and a floor so wide that our guide told us you could fit several city blocks inside and still have room to spare. Our voices just vanished into it. Stalactites hung down like something dripping in slow motion, and in a way they were — every formation in there took over a million years to grow into the shape we were looking at, drop by mineral drop, long before either of us existed.

What stuck with me most, though, wasn’t the size — it was the river itself, black and fast at the bottom of the cave, cutting through limestone with an indifference that made me feel very small in the best way. Lia kept stopping to point out bats stirring somewhere up in the dark, and I kept thinking about how this system just kept going, further than any tour would take us, deeper into Camuy, Hatillo and Lares than daylight has ever reached.

When to go: We went on a weekday morning and I’m glad we did — go early if you can, since the park caps the number of daily tour tickets and they do sell out, especially once the weekend crowds show up.