Cenotes are enormous sinkholes, resulting from the collapse of limestone due to the passing of water underneath. Yucatán is formed by limestone as far as 2 km deep. The water has created whole systems of caves inside the limestone. On the special maps one can see that many cenotes are interconnected by subterranean tunnels. The cenotes played an important role in the life of the Maya – as sources of water as well as ritual sites. Up until this days traces of ancient sacrifices come up in cenotes.
El Gran Cenote is found 3km to the West of Tulum. I biked there through an empty road through the jungle.
A cenote looks essentially like a huge pit. It is quite unbelievable that down below, under the water, it divides and protrudes into every direction like a giant octopus.
I was snorkelling just below the surface of water and was amazed to observe the divers in the deep lighting the underwater caves with flashlights. The practice is called spelunking I believe. These divers went seriously deep to the parts where there is no sunlight. They say the most dangerous in such trips is to lose orientation and to panic. Therefore the weakest member defines the allowed difficulty of the attempt.