Mindanao, island, the second largest (after ) in the , in the southern part of the archipelago, surrounded by the , , , and seas. Irregularly shaped, it measures 293 miles (471 km) north to south and 324 miles (521 km) east to west. The island is marked by peninsulas and is heavily indented by the Davao and Moro gulfs in the south and by Bay in the north. The long, semicircular (west) extends southwesterly toward the and , and the Cotabato and peninsulas extend south and north, respectively.Mindanao, Philippines(more)Rugged, faulted mountains and occur in many areas. , at 9,692 feet (2,954 metres), is an active volcano in the southern part of the central highlands; it is the highest peak in the Philippines. The island has narrow coastal plains, and broad, fertile basins and extensive swamps are formed by the and river systems. (Lake Sultan Alonto), created by a lava dam, has an area of 134 square miles (347 square km). The island has a marsh-game refuge and bird sanctuary. The rare is found on Mindanao.Mindanao is a outpost in the predominantly Philippines. Although Muslims are no longer a majority, Islamic culture is evident; there are many mosques, and distinctive brassware, including the kris, or dagger, is manufactured. The autonomous region of Muslim Mindanao—consisting of territory in western and southwestern Mindanao along with a number of nearby islands, including and —was established in 1990., Mindanao (/ ˌ m ɪ n d ə ˈ n aʊ / ⓘ MIN-də-NOW) is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of the same name that also includes its adjacent islands, notably the Sulu Archipelago., Mindanao, island, the second largest (after Luzon) in the Philippines, in the southern part of the archipelago, surrounded by the Bohol, Philippine, Celebes, and Sulu seas. Irregularly shaped, it measures 293 miles (471 km) north to south and 324 miles (521 km) east to west..