Río SecretoThousands of years ago, the entire Yucatán Peninsula was under water, as evidenced by its massive network of rivers that flow beneath the region’s limestone surface. No place better presents the area’s captivating caverns and underground water systems than majestic Río Secreto, a nature park just south of Playa del Carmen that offers adventurous travelers wide-ranging cave tours. Extending for miles, its river system wasn’t discovered until 2006, when a local man accidentally stumbled across an entrance while chasing an iguana through the jungle. When you go, guides lead you through a maze of stalactites and stalagmites that ends with a swim in subterranean waterways that vary based on the path you choose.
The Secret Mayan Underworld in Mexico
Located in Playa del Carmen, the caves at Río Secreto are one of many fun day trips to be made from Cozumel. The Yucatán Peninsula is pocked with sinkhole-created cenotes—a kind of natural swimming pool—and yes, visitors can swim in them! The Río Secreto experience involves walking through a cave to reach one of these cenotes and, if you'd like, taking a dip in it. Bring water shoes, and wear clothes you don't mind getting dirty.