Just a few kilometres north of Aibonito, the Cañón de San Cristóbal is a rugged 9km-long gorge created by the raging waters of the Usabón, Aibonito and Piñonas rivers. Tucked away in the folds of rolling hills and farmland, the canyon is hard to make out from above, its sheer sides smothered in dense subtropical foliage, clinging moss and swaying ferns, but the drop down in places reaches a hair-raising 230m. Exploring the gorge takes some effort, but that’s part of the appeal: clamber to the bottom and you’ll enter a lost world of plunging waterfalls (some the island’s highest), churning pools and a plethora of endemic Puerto Rican flora, freshwater fish, snakes and rare birds such as the red-tailed hawk. In between the rocks it’s still possible to see overgrown TVs and abandoned fridges, rusting and half-hidden in the jungle, a reminder that this was used as a municipal garbage dump for over twenty years. In 1974 the Conservation Trust stepped in to halt this shocking state of affairs, and today around 5 square kilometres of the gorge are protected.