Ik Kil Cenote
Another view down in a cenote near the ruins of Chichen Itza. History tells of the Maya culture viewing these areas as very sacred, believing that they were gateways to the afterlife. There is also the problem that there are almost no rivers or lakes in the Yucatan peninsula, so cenotes became building sites for cities to provide the people with a water source.
To give a little sense of scale of this guy, take a look in the upper left, where you see a straight line, that is a wall overlooking the cenote. The wall was about waist high, and I couldn’t reach the ceiling. It was easily 40m deep and 60m wide. I also read that the water continues another 25m down.