There was a time when I knew as much about Puerto Rico as I do about Quantum Physics. Nada. My cultural and historical references for this exotic U.S. territory were limited to lyrics from 1960s musicals (i.e. the catchy “I want to live in America” tune sung in West Side Story, that paints Puerto Rico in a somewhat disparaging light). So what to expect from this Caribbean nation of 3.6 million people, nestled between the Dominican Republic and the U.S. Virgin Islands? A hub for adventure activities across rainforests, oceans, canyons and caves, the country has a lot to offer the thrill-seeking tourist.

A hub for adventure activities across rainforests, oceans, canyons and caves, the country has a lot to offer the thrill-seeking tourist. On a recent trip, I explored Puerto Rico’s wild side. Eager to get my climb on, I signed up for a day-long excursion offered by Aventuras Tierra Adentro, a Puerto Rican-owned outfitter that runs caving, zip-lining, climbing up ferratas (vertical pathways equipped with cables, metal rebars and ladders) and spelunking trips through the famous Rio Camuy. One of the most popular natural attractions in Puerto Rico, Rio Camuy is a network of natural limestone caves and underground waterways. The cool thing is that Aventuras Tierra Adentro is the only company with rights to access the Angeles Cave, an underground gem that’s part of the Rio Camuy cave system.

There I was, dangling like bait above a lush abyss of giant ferns, mosses and neon-orange orchids. Swinging ever so gently on a rope, suspended by a system of pulleys and belaying devices, I said a prayer and hoped I’d make it home alive to tell my family about Puerto Rico’s magestic rainforest canopy.

A hub for adventure activities across tropical rainforests, oceans, canyons and caves, the country has a lot to offer the thrill-seeking tourist. On a recent trip, I explored Puerto Rico’s wild side. Eager to get my climb on, I signed up for a day-long excursion offered by Aventuras Tierra Adentro, a Puerto Rican-owned outfitter that runs caving, zip-lining, climbing up ferratas (vertical pathways equipped with cables, metal rebars and ladders), and spelunking trips through the famous Rio Camuy. One of the most popular natural attractions in Puerto Rico, Rio Camuy is a network of natural limestone caves and underground waterways. The cool thing is that Aventuras Tierra Adentro is the only company with rights to access the Angeles Cave, an underground gem that’s part of the Rio Camuy cave system.

Our day excursion began with a series of lessons and safety briefings. Company owner and guide Rossano Boscarino brought our group of intrepid travelers up to speed on everything we’d need to know about the day’s activities, from rappelling to climbing, free jumping to body rafting through underground rivers. Rossano’s team fed us valuable caving info with a spoonful of comic relief, adding vaudevillian skits, sound effects, and sassy double entendres for entertainment value. With the basics under our belts, our group suited up in the adventure armor of the day.

I strapped on my lamped helmet, slipped into my harness, and tightened all necessary straps and clips before launching down the first zip-line. Dangling high above the rainforest, I zip-lined across a mossy green canopy, soaring over the great Angeles sinkhole. As the metallic trolley pulleys sped angrily along the galvanized aircraft cable, the canyon was filled with sounds that conjured up images of giant zippers and gigantic prehistoric dragonflies.

We soared across a series of zip-lines and rappelled over the rock ledge, dropping down into the mouth of the cave. As someone who doesn’t love heights, it was a challenge to dangle helplessly there above the canyon, overlooking a plunge that would mean certain death. My heart was pounding, my palms sweaty, a dreadful feeling in the pit of my stomach that left me worrying that perhaps I’d made a very bad decision. Allow me to bring you into the mind of someone who hates heights, yet has chosen to descend down a rock face using merely a rope. Raw fear. I argue that it’s totally rational to be afraid of heights. Our bodies are designed for self-preservation, not chucking oneself over the steep ledge of a scraggly rock face. Yet for the modern man/woman, fear is the four-letter word that we no longer let rule us. Fear is the feeling that drives many adventurers to play harder, go further and descend into weird unknown Puerto Rican caves. So I worked through the fear, swept it aside, wiped my sweaty, anxious palms on my Eddie Bauer Travex pants and pushed on. Loosening the rope, inch by inch, I was finally allowed a quiet moment of actual enjoyment—a rare bird’s-eye view over Puerto Rico’s rainforest canopy—before lowering myself down into the canyon to the mouth of the cave.

Inside the cave, our team of explorers investigated its large chambers by headlamp. Zip-lining through the darkness, on the watch for flash floods, we marveled at huge stalagmites, stalactites and other bizarre calcium formations created millions of years ago. Depending on the season and water level, some groups can experience mudslides, body rafting and free jumps into darkness. With the smell of bat poop in the air and the sound of scuttling translucent spiders (the size of a man’s hand), there is something truly primordial about cave exploration.

Overall, it was a jam-packed day of rappelling down limestone ravines, soaking in subterranean rivers, climbing up ferratas, and observing the fossils of sea creatures that lived long ago.  Post-caving, I enjoyed a cold beer and a strong sense of accomplishment. The pleasure derived from adventuring into the unknown was worth the risk. It was worth the fear, the doubt, the dreadful butterflies in my gut. It was an epic journey into the heart of the wild Rio Camuy…into the belly of the limestone rock beast.