Borneo, island in the extreme southwestern part of the . It is the third largest island in the world, surpassed in size by only and .Borneo is situated southeast of the in the Greater group of the . The island is bounded by the to the northwest, the to the northeast, the to the east, and the to the south—the latter separating Borneo from the island of . The separates Borneo from the island of (Sulawesi) to the east and southeast, and a series of shallow seas and straits lie between Borneo and the island of to the west.Sultan Omar Ali Saifuddien MosqueSultan Omar Ali Saifuddien Mosque at dusk, Bandar Seri Begawan, Brunei.(more) constitutes the largest political component of the island (in known as ), its territory divided into five provinces: , , , , and . Along the northwest coast and northern tip lie and , two constituent states of that are often collectively called , and between them is the Islamic sultanate of . Area (including adjacent islands), about 292,000 square miles (755,000 square km). Pop. (2015) five provinces of Kalimantan (including adjacent islands), 15,320,017; (2010) Sabah and Sarawak, 5,677,882; (2014 est.) Brunei, 411,900. Land Kinabalu, MountMount Kinabalu, Sabah, East Malaysia, highest peak on Borneo.(more)Borneo lies astride the . It has a length of 830 miles (1,336 km) from northeast to southwest and a maximum breadth of 600 miles (960 km). The island is largely mountainous, although there are extensive lowlands, especially in Central Kalimantan and Sarawak, that are often swampy along the coasts. A long series of mountain ranges extend southwest across the island from in the far northeast, which, at an elevation of 13,455 feet (4,101 metres), is the island’s greatest height and is also the tallest peak in Malaysia. Ranges in the central spine include the Crocker, the Nieuwenhuis, and the Muller mountains. The Kapuas Hulu Mountains branch westward from the central core along the border between Sarawak and West Kalimantan, and a separate and discontinuous series of ranges parallel the east and southeast coasts in East and South Kalimantan. Sarawak: riverCanoe transportation on a river in Sarawak, East Malaysia, on Borneo.(more)A large part of Borneo is drained by navigable rivers, which represent the principal and often the only lifelines of trade and commerce. The main rivers of Kalimantan are the in the west and the in the east. Farther north, as the island narrows, few rivers are navigable for more than 100 miles (160 km), often much less, a condition largely responsible for the northern interior of Borneo remaining, until recently, one of the least-known parts of the world. The main river of East Malaysia is the in Sarawak., Borneo (/ ˈbɔːrnioʊ /) is the third-largest island in the world, with an area of 748,168 km 2 (288,869 sq mi), and population of 23,053,723 (2020 national censuses). [1][2][3] Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda Islands, located north of Java, west of Sulawesi, and east of Sumatra., Borneo, island in the extreme southwestern part of the Pacific Ocean. It is the third largest island in the world, surpassed in size by only Greenland and New Guinea. Borneo is situated southeast of the Malay Peninsula in the Greater Sunda Islands group of the Malay Archipelago..