Montezuma's Well is a sinkhole, a collapsed underground limestone cavern filled with water. More than a million gallons of water a day flow continuously, providing a lush, verdant oasis in the midst of surrounding desert grassland. Montezuma's Well is 368 feet across and 55 feet deep; it sits at an elevation of 3,618 feet.
Locating the source of the well's water has researchers baffled. Tests using gas and dye have been performed, but so far, no connection has been established between the well's water and any other water source in the area. For trivia lovers, in May 1948, the U.S. Park Service used scuba equipment for the first time ever, to explore Montezuma's Well.