A group of divers have connected two underwater caverns in eastern Mexico to reveal what is believed to be the biggest flooded cave on the planet, a discovery that could help shed new light on the ...

Sótano de las Golondrinas, or Cave of Swallows, is the largest pit cave in the world — an over 1,200-foot drop from top to bottom. It's also home to thousands of birds, who spiral out of the ...

swimming and access to a small bar of refreshing drinks and fruits, and an "Amazing Underground Adventure" that takes you through caves where you can snorkel and see a range of incredible rock ...

The bright turquoise water contrasts with the caramel- and mocha-colored rock formations within the caves, which include stalactites and stalagmites. Visitors can swim in the river, climb through ...