Location: Indonesia is located in Southeast Asia. The
approximate geographic center is at 5ES and 120EE. It
lies between the Indian and Pacific oceans and between
the continents of Asia and Australia, south of Malaysia
and the Philippines, and northwest of Australia.
Size: Estimates of the size of Indonesia’s total area vary. Officially, the Indonesian government says the total land area is 1.9 million square kilometers and total sea area, 7.9 million square kilometers, including an exclusive economic zone. Academic sources report a total land area of 2,027,087 square kilometers plus 3,166,163 square kilometers of territorial waters and note that the country measures about 5,100 kilometers at its greatest east-west extent, and about 1,888 kilometers at its greatest expanse north to south. According to U.S. Government sources, Indonesia has 1,826,440 square kilometers of land, some 93,000 square kilometers of water area (the sum of all water surfaces delimited by international boundaries and/or coastlines, including inland water bodies, such as lakes, reservoirs, and rivers) for a total area of 1,919,440 plus a 7.9 million-square-kilometer maritime area.
Land Boundaries: Indonesia’s land boundaries total 1,758 kilometers, including 1,107 kilometers with Malaysia, 820 kilometers with Papua New Guinea, and 288 kilometers with East Timor.
Length of Coastline: Indonesia’s coastline totals 54,716 kilometers on the Indian Ocean, Strait of Malacca, South China Sea, Java Sea, Sulawesi Sea, Maluku Sea, Pacific Ocean, Arafura Sea, Timor Sea, and other smaller seas.
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Maritime Claims: Indonesia claims a 12-nautical-mile territorial sea and a 200-nautical-mile exclusive economic zone, measured from claimed archipelagic straight baselines. The total area claimed by the Indonesian government, including Indonesia’s territorial sea and an exclusive economic zone, encompasses 7.9 million square kilometers.
Topography: Indonesia is the largest archipelagic nation in the world. It encompasses more than 17,000 islands (17,508 according to the Indonesian Hydro-Oceanographic Office). About 6,000 of these islands are named, and about 1,000 are permanently settled. The five main islands are Java, Kalimantan, Papua (formerly called Irian Jaya), Sumatra, and Sulawesi. There are two major archipelagos, Nusa Tenggara and Maluku, and about sixty smaller archipelagos. The larger islands of Indonesia are mountainous, with some peaks reaching 3,800 meters above sea level on the western islands and as high as 5,000 meters on Papua. The highest point is Puncak Jaya (5,030 meters) on Papua. The region is tectonically unstable with some 400 volcanoes, of which 100 are active.
Principal Rivers: Indonesia’s waterways total 21,579 kilometers. The principal rivers are the Musi, Batanghari, Indragiri, and Kampar rivers on Sumatra; the Kapuas, Barito, and Mahakam rivers on Kalimantan; the Memberamo and Digul rivers on Papua; and the Bengawan Solo, Citarum, and Brantas rivers on Java, which are used primarily for irrigation.
Climate: Indonesia’s maritime equatorial climate typically produces high, even temperatures and heavy rainfall; temperature variations are generally due to island structure (elevation) and time of day, while rainfall may vary across the archipelago as a result of many different factors, among them monsoon patterns, which themselves vary according to location. Average temperatures at or near sea level range from about 23EC to 31EC. In most of the country, rainfall is comparatively heavy throughout the year, with a pronounced rainy season roughly between December and March. East of Surabaya, however, a dry season is increasingly noticeable, especially between June and October. The high elevations of Sumatra, Kalimantan, Sulawesi, and Papua receive about 3,000 millimeters of rain annually; lower elevations, and much of Java, receive 2,000 or more millimeters; farther east rainfall ranges between 1,000 (Sumba) and 2,000 millimeters per year (Bali and Timor).
Natural Resources: Petroleum and natural gas are among Indonesia’s most important natural resources. Indonesia is the world’s largest exporter of liquefied natural gas. Most petroleum production is on central Sumatra, but Java also has significant production, and there are substantial proven offshore reserves. There are also large coal reserves. Other significant minerals are bauxite, copper, gold, iron, manganese, nickel, sulfur, silver, and tin. An important nonmineral resource is timber.
Land Use: According to 2001 estimates, 11.3 percent (206,753 square kilometers) of Indonesia’s total land area is arable, and land planted in permanent crops, including an irrigated area of 48,150 square kilometers, represents 7.2 percent of the total (132,051 square kilometers). There are 1,619,687 square kilometers of nonarable land and land not under permanent crops.
Environmental Factors: Indonesia’s geography leaves the nation vulnerable to severe flooding, unpredictable drought and plant pest attacks, volcanic activity, and earthquakes, which are sometimes associated with tidal waves (tsunami). The most important environmental issues associated with human activities are forest degradation (unregulated cutting, fires, smoke and haze, and erosion); water pollution from industrial wastes and sewage; air pollution from motor vehicles and industry in urban areas, and generally from smoke and haze caused by forest fires; and threats to biodiversity and rare plant and animal species.
Time Zones: Since January 1, 1988, Indonesia has had three time zones: Western Indonesia Standard Time (Greenwich Mean Time—GMT—plus seven hours), covering all provinces on Sumatra and Java, and the provinces of western and central Kalimantan; Central Indonesia Standard Time (GMT plus eight hours), covering the provinces of eastern and southern Kalimantan, all provinces on Sulawesi, and the provinces of Bali, West Nusatenggara, and East Nusatenggara; and Eastern Indonesia Standard Time (GMT plus nine hours), covering the provinces of Maluku and Papua.