Mindanao, island of the Philippines, the second largest, after Luzon and southernmost of the country's major islands. The island is 500 km (300 mi) long and very irregular in shape. The Zamboanga Peninsula in the west is nearly divided from the main part of the island by Iligan Bay on the north and Illana Bay on the south. The coastline is marked with many bays and headlands, which afford shelter to ships during storms. The island is mountainous, and the mountains are covered with forests of teak, ironwood, cypress, ebony. The loftiest summit is the volcano Mount Apo, 2,954 m (9,692 ft) above sea level. The principal rivers are the Mindanao and the Agusan. The soil is exceedingly fertile and produces corn, rice, coconuts, bananas, pineapples, and abaca, or Manila hemp; stock farming is also an important economic contributor. Gold, copper, iron, and coal are the chief mineral resources. The chief cities on the island are Zamboanga, Davao, and Cagayan de Oro. Population (1990) 14,536,000.