The summit and crater lake of Mount Pinatubo lies within Botolan municipality in Zambales, near the tripoint of Zambales, Pampanga and Tarlac provinces. This volcano, once considered dormant, erupted violently in June 1991. The former summit of the volcano was obliterated by the massive eruption and replaced by a wide caldera, within which Lake Pinatubo is situated. With an average depth of , Lake Pinatubo is the deepest lake in the Philippines. The highest point of the caldera rim is above sea level, some lower than the pre-eruption summit. A vast portion of the Zambales province acquired desert-like features in 1991, after being buried by more than of lahar.