The Philippines, an archipelago of 7,641 islands, features the Cordillera Central on Luzon peaking at Mount Pulag (2,928 m)—Luzon's highest—with pine forests above 2,000 m. Mindanao's Apo (2,956 m)—highest overall—is a stratovolcano with 35 peaks over 2,000 m. Formed by Philippine Sea subduction 30 million years ago, the Sierra Madre reaches 1,800 m. Mayon volcano (2,463 m) has a perfect cone. Bohol's Chocolate Hills (1,200 mounds, 30-50 m high) are limestone karst. This volcanic topography includes 7,100 islands and 24 national parks with Philippine eagles and tarsiers.