Montezuma Well is a natural limestone sinkhole near Rimrock in central Arizona, fed by an underground spring that releases about 1.5 million gallons of water daily and maintains a nearly constant basin level even in drought. Despite its name, it has no connection to the Aztec emperor Montezuma. Formed within the Verde Limestone, its highly carbonated, arsenic-rich water supports no fish but sustains several endemic species found only there. People have used the Well for thousands of years; Indigenous communities, especially the Southern Sinagua, diverted its steady outflow into canals to irrigate surrounding land, and ruins around the rim show its long importance, including its sacred meaning for the Yavapai.