Throughout the Yucatán Peninsula, there is a network of cenotes that span the entirety of the region. In a nutshell, cenotes are sinkholes of porous limestone filled with mineral-rich waters. These underwater caves and caverns held much importance to the ancient Mayan culture as they provided a consistent water supply that never ran out. Cenotes also held religious significance and in some extreme cases, were used for human sacrifice as a way of communication with the rain god, Chaac. Nevertheless, cenotes are a popular attraction to both the locals and visitors and make a very reasonable and enjoyable day trip.