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