Rio Secreto is known as Mexico’s underground river. While its name lends itself to the clandestine, over the years the spot has become a popular tourist attraction. Rìo Secreto is a series of caves carved out by the flow of an ancient underground river in Mexico. While the reserve is most famous for its large half-sunken cavern—a popular diving spot—you can also explore eerie passageways, swim in the river, and admire dripping stalactites, stalagmites, and colorful mineral formations.
