This report describes in detail four water spray coolers designed for cooling deep underground mines and discusses the performance of three of them in deep-mine field tests. The four spray coolers were designed and built as part of a Bureau of Mines program to investigate direct-contact (warm air to cool water) spray cooling systems. A single-stage cooling unit was tested in a New Mexico uranium mine, and a two-stage cooler and a three-stage cooler were tested in a South Dakota gold mine. To data, all three coolers have performed well under in-mine conditions and have required only minimal maintenance. Tests on a fourth cooler, a three-stage unit, are under way, but have not been completed.