Explore the natural wonders of the Rio Secreto underground river, the Yucatan Peninsula's hidden gem. Swim amid thousands of stalactites and stalagmites, and learn about the river's geology.

Immerse yourself in a world of geological wonders with a guided tour of this spectacular subterranean river. Previously known as Pool Tunich, Rio Secreto boasts more than 7.5 miles (12 km) of breathtaking semi-sunken caves.

Put on your specialized gear, and follow your knowledgeable guide on a journey of discovery while learning interesting facts about the nature reserve's geology. Walk and swim through mineral-rich waters, and marvel at the sight of thousands of calcified stalactites and stalagmites lining the 0.4-mile (600-m) route. Then, enjoy some nutritious snacks, and kick back in the middle of the jungle in a traditional hammock.