Zambales lies on the western shores of Luzon island along the West Philippine Sea. Its shoreline is rugged and features many coves and inlets. The Zambales Mountains in the eastern length of the province occupies about 60% of the total land area of Zambales. Subic Bay, at the southern end of the province, provides a natural harbor, and was the location of the U.S. Naval Base Subic Bay until its closure in 1992.