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
Apo Reef and is about in depth. Likewise, reef limestone and coralline sand on the east and southeastern sides dominantly underlie the area. The main geographical feature of Apo Reef is submerged, but three islands mark it on the surface: the Apo Island, Apo Menor (locally known as "Binangaan") and Cayos del Bajo ("Keys of the bank", locally known as "Tinangkapan"). The islands are uninhabited. Since the declaration of “no-take-zone” policy at Apo Reef Natural Park in 2007, only protected area personnel and members of the Task Force MARLEN (Marine and Apo Reef Law Enforcement for Nature), who are task to implement