Cordillera Central (Luzon) Sierra Madre Mountains, the longest mountain range in the country, through the Caraballo Mountains in Nueva Vizcaya province. During Spanish colonial period, the whole range was called "Nueva Provincia", (New Province). The Cordillera Central is the highest mountain range in the Philippines. It comprises about 1/6 of the whole Luzon island with a total area of . The highest mountain in the range, Mount Pulag, is also the highest mountain on Luzon Island at . It is officially the third highest mountain in the country after Mount Dulang-dulang and Mount Apo on Mindanao Island, the second largest island of the
Mount Apo of ; with two peripheral areas of and as buffer zones, provided for its management and for other purposes. Although a declared a Natural Park, the current climbing trails are littered with rubbish by irresponsible climbers, opening paths for soil erosion across the already denuded mountain sides. Some mountain and social climbing groups conduct climbs after the Holy Week/Easter, the peak climbing season, to clean the affected areas. In 1987, the National Geographic Society based in Washington, DC in the United States, published a book entitled, ""Our World's Heritage"", where Mount Apo was noted as a 'site of Word Heritage