While the best-known cenotes are large open water pools measuring tens of meters in diameter , such as those at Chichén Itzá in Mexico , the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water .
While the most well-known cenotes are large open water pools measuring tens of metres in diameter , such as those at Chichén Itzá , most cenotes are smaller sheltered sites and do not necessarily have any surface exposed water .