You can't be in the Yucatan too long before you start wondering how people could make a life here year round. You see the archeological sites with beautiful cities, temples, and agricultural areas; and except for right along the coast you don't see water. Especially in the northern Yucatan there are no obvious rivers, creeks, or lakes.
There is a lot of rain in the Yucatan at certain times of the year. The rainy season runs from June through October. It is associated with the Mexican monsoon which draws warm, moist air from the Gulf of Mexico and Caribbean landward. Yet, there are long very dry stretches. So where did the daily water come from for the people of the peninsula?
Part of the answer is that the indigenous people were acutely aware of the seasonal changes and they went to great lengths to prepare for those changes. In Uxmal, for example, there was an underground cistern (chultun) for each family unit of twenty or more people. These cisterns were carefully engineered so that the city's rainwater drainage system filled the cisterns providing water storage for the dry periods.
Another important answer to the question of water source lies in the porous limestone from which that most of the Yucatan is composed. There are systems of underground rivers and lakes throughout the Yucatan in this limestone and many are interconnected. Sometimes these rivers or lakes are exposed by a collapse of the limestone above them and deep natural sinkholes that the Mayas called cenotes (dzonot) are formed. These cenotes may appear as a lake, or sometimes there are only tiny openings into these water systems. Through these openings you may enter into a cavern often filled with beautiful stalagmites (drippers).
These caverns open onto the underground rivers and lakes. The Maya found many of these cenotes and often built large cities near them. These cenotes were their principal water source.
When we arrived at the second cenote we went swimming. The water that gathers in these subterranean cenotes is a crystal clear turquoise color with a very pleasant temperature of 78° F (25.5º C). There were fish easily visible swimming about, and it felt great to jump in as the temperature above ground was around 100° F (37.8º C).
Below is a short clip I took of a pony pulling a tram through the heavily overgrown henequen plantation. Give it a minute to load.