The Water Underground

Mauricio Ramos

Once upon a time, an iguana scurried down a hole in the Riviera Maya and a local farmer followed it. Below the ground the farmer discovered a hidden world: a río secreto, or secret river. Think Harry Potter meets Mother Nature’s Cirque du Soleil: caverns, crystal-clear water, albino fish, dripping rock formations.

The man who happened upon the river, not far from the coastal hotels and resorts here, approached Alltournative—a tour operator known for its sustainable practices and focus on Mayan traditions—to help him share his find, and today the company offers just 70 people a day the chance to explore the river in small guided groups. Hikers use custom-fitted helmets equipped with powerful lights to illuminate the caves, the route through which isn’t at all strenuous. You’ll want to move slowly, though, to absorb the stunning surroundings; it took me an hour and a half to venture a mere 500 yards. A half-day excursion is $80 per person (800-507-1092;