These giant sinkholes, known as cenotes, dot the limestone landscape of the Yucatán. Some, like at Chichen Itza, are open wells; some are completely subterranean; and many, like this one, are sort of in between. Because the Yucatán lacks river systems, human settlements tended to graviate to cenotes. Zací sustained the Mayan town that was here before the Spanish, and probably sustained the Spanish as well, early on. The hot, humid air this evening was charged with the nervous electricity of an approaching storm- In the cenote, about a half-dozen people were swimming in the deep, deep water, keeping company with the many black fish. Valladolid, Yucatán, México August 4, 2010 Valladolid is an incredible place- The ancient Maya had a town here called "Zací", which was destroyed by the Spanish under a nephew of the conquistador Montejo family. They had established a town further away, but plagued by mosquitos, they arrived here and established Valladolid on March 24, 1545. The Mayans of the region, of course, did not take kindly to this invasion and, in the face of horrific horrific exploitation, staged numerous revolts over the following centuries, culminating in the Caste Wars of the 1840's, in which the town was sacked and many of the residents slaughtered. In other parts of Mexico, the tensions and fallout stemming from the Spanish colonial system still run very high, but here there seems to be some peace at the moment. It's a small town, and you seem to run into the same people over and over again. Due its proximity to some major archeological sites, it has begun to see more tourism over the past ten years- predominantly European backpacker types- We twice bumped into some Germans who were traveling through the Yucatán and Central America. As far as we could tell, we were the only Americans in town. It's a compact, densely packed place and there are a number of modest hotels near the zócalo and a handful of exceptional restaurants. Under the extreme tropical sun (by mid-afternoon, you can't walk half a block without being drenched in sweat), the narrow, brightly colored streets are a flurry of activity -stores specializing in leather and clothing; -food vendors selling strange fruits, medicines, and streetfood; -bicycles, cars, traffic cops; -old Mayan women dressed in traditional huipiles sewing embroidery on the sidewalk or walking the streets in pairs. The language here is accented by Mayan, and occasionally you hear pure Yucatec Mayan being spoken, as it is still the first language of many.