Subic Bay is a bay on the west coast of the island of Luzon in Zambales, Philippines, about northwest of Manila Bay. It is an extension of the South China Sea, and its shores were formerly the site of a major United States Navy facility named U.S. Naval Base Subic Bay, it is now the location of an industrial and commercial area known as the Subic Bay Freeport Zone under the Subic Bay Metropolitan Authority. The bay was long recognized for its deep and protected waters, but development was slow due to lack of level terrain around the bay.