Cenote Azul, Yuc., Mexico
Swimming HolesThe unique geology of the Yucatan has also created a unique attraction, the area’s cenotes. These sinkholes were formed when the limestone bedrock collapsed in a sinkhole that exposes the groundwater below. The cenotes were long one of the few sources of fresh water in this region without rivers or lakes, and they were also believed by the Maya to be passages to the afterlife—the Sacred Cenote at Chichén Itza is perhaps the most famous such gateway. Other cenotes, like the Cenote Azul shown here, are open to swimmers for a small fee.
Photo by Graeme Churchard/Flickr.