A cenote is a natural sinkhole or well that is often filled with water. These geological formations are typically found in limestone regions, where the rock has eroded over time, creating a depression. Cenotes are common in the Yucatán Peninsula of Mexico, where they were historically significant to the Maya civilization for water supply and religious rituals. Cenotes can vary in size and depth, and they may be open to the sky or partially covered. They often feature clear, fresh water and are popular for swimming, snorkeling, and diving. Many cenotes also host unique ecosystems, supporting various plant and animal species.