GEOGRAPHY OF INDONESIA: SIZE, BOUNDARIES, PEOPLE

GEOGRAPHY OF INDONESIA

topographical map of Indonesia, 2002

Indonesia is the largest archipelago and country composed solely of islands in the world. Located north of Australia and south of the Philippines and the Malay Peninsula, it occupies a strategic location along major sea lanes from the Indian Ocean to the Pacific Ocean and is the largest and most widely-spread country in Southeast Asia. Satellite imagery analysis done in the early 2000s, revealed that it had 18,108 islands, more than 1,000 islands than previously thought, at high tide. There are even more at low tide. [Sources: Library of Congress, CIA World Factbook]

Of the 13,466 recognized islands of Indonesia, 922 are recognized as being permanently inhabited by the United Nations; Indonesia is one of the countries along the Ring of Fire, which is a belt bordering the Pacific Ocean that contains about 75 percent of the world's volcanoes, up to 90 percent of the world's earthquakes, and 80 percent of tsunamis. Despite having the fourth largest population in the world, Indonesia is the most heavily forested region on earth after the Amazon.

Indonesia extends latitudinally from 11° S to 4° N, which gives its to some degree climate unity, and stretches west to east for more than 4,800 kilometers (2,983 miles) between 95° E and 141° E. Geographic coordinates: 5 00 S, 120 00 E. Land boundaries: total: 2,958 kilometers (1,838 miles); border countries: Malaysia 1,881 kilometers (1,168 miles); Papua New Guinea 824 kilometers (512 miles); Timor-Leste 253 kilometers (157 miles). Maritime claims: territorial sea:12 nautical miles (22.2 kilometers); exclusive economic zone: 200 nautical miles (370 kilometers). These are measured from claimed archipelagic straight baselines. [Source: CIA World Factbook]

Main Island Groups: Consisting of the former Dutch East Indies territory, Indonesia's main island groups are 1) the Greater Sunda Islands (Java, Sumatra, Borneo (Kalimantan) and Sulawesi); 2) the Lesser Sunda Islands (Bali, Flores, Sumba, Lombok and Timor); 3) the Moluccas (Ambon, Seram and Halmahera); and 4) the Riau Archipelago. After years of dispute with the Dutch, West New Guinea (now Papua and West Papua) was formally annexed by Indonesia in August 1969. The most important islands, both culturally and economically, are Java, Bali and Sumatra. [Source: Columbia Encyclopedia, 6th ed., Columbia University Press]

Time Zones: Groups: Located on the equator, the archipelago experiences relatively little change in the length of daylight hours from one season to the next; the difference between the longest day of the year and the shortest is only 48 minutes. Sunrises and sunsets occur quickly with relatively little twilight. The archipelago stretches across three time zones: Western Indonesian Time—seven hours in advance of Greenwich Mean Time (GMT)—applies to Sumatra, Java, and west and central Kalimantan; Central Indonesian Time—eight hours ahead of GMT—is observed in Bali, Nusa Tenggara, south and east Kalimantan, and Sulawesi; clocks are set to Eastern Indonesian Time—nine hours ahead of GMT—in the Malukus and Papua. The boundary between the western and central time zones—established in 1988—is a line running north between Java and Bali through the center of Kalimantan. The border between the central and eastern time zones runs north from the eastern tip of Timor to the eastern tip of Sulawesi. Indonesia does not operate daylight- saving time in the summer.

Administrative divisions: 35 provinces ( provinsi-provinsi , singular - provinsi ), 1 autonomous province*, 1 special region** ( daerah istimewa ), and 1 national capital district*** ( daerah khusus ibukota ); Aceh*, Bali, Banten, Bengkulu, Gorontalo, Jakarta***, Jambi, Jawa Barat (West Java), Jawa Tengah (Central Java), Jawa Timur (East Java), Kalimantan Barat (West Kalimantan), Kalimantan Selatan (South Kalimantan), Kalimantan Tengah (Central Kalimantan), Kalimantan Timur (East Kalimantan), Kalimantan Utara (North Kalimantan), Kepulauan Bangka Belitung (Bangka Belitung Islands), Kepulauan Riau (Riau Islands), Lampung, Maluku, Maluku Utara (North Maluku), Nusa Tenggara Barat (West Nusa Tenggara), Nusa Tenggara Timur (East Nusa Tenggara), Papua, Papua Barat (West Papua), Papua Barat Daya (Southwest Papua), Papua Pegunungan (Papua Highlands), Papua Selatan (South Papua), Papua Tengah (Central Papua), Riau, Sulawesi Barat (West Sulawesi), Sulawesi Selatan (South Sulawesi), Sulawesi Tengah (Central Sulawesi), Sulawesi Tenggara (Southeast Sulawesi), Sulawesi Utara (North Sulawesi), Sumatera Barat (West Sumatra), Sumatera Selatan (South Sumatra), Sumatera Utara (North Sumatra), Yogyakarta**. [Source: CIA World Factbook]

Size and Landcover of Indonesia

NASA image of Indonesia

Area of Indonesia: total : 1,904,569 square kilometers about 741,000 square miles). Of Indonesia’s total area 1,811,569 square kilometers (699,451 square miles) is land and 93,000 square kilometers (35,907 square miles) is inland seas (straits, bays, and other bodies of water). Coastline: 54,716 kilometers (34,000 miles); Elevation: highest point: Puncak Jaya 4,884 meters (16,023 feet); lowest point: Indian/Pacific Oceans 0 meters; mean elevation: 367 meters (1,204 feet). [Source: CIA World Factbook]

In terms of area, Indonesia is the 15th largest country in the world. Straddling the equator and located where the Pacific and Indian Oceans meet, it covers an area roughly the size of Mexico or three times the area of Texas. Indonesia stretches 5,271 kilometers (3,275 miles) from east to west along the equator, across three times zones from Malaysia in the west to Papua New Guinea in the east, and 2,210 kilometers (1,373 miles) from north to south from northern Kalimantan in Borneo in the north to a small group of islands south of Timor in the south. The distance from its furthest western point in the Indian ocean to its furthest eastern point in the Pacific is the roughly equal to the distance between California and Bermuda or London and Baghdad. [Sources: Library of Congress, CIA World Factbook; Junior Worldmark Encyclopedia of Physical Geography, Gale Group, Inc., 2003]

The additional surrounding sea areas bring Indonesia's generally recognized territory (land and sea) to about 5 million square kilometers. The government, however, also claims an exclusive economic zone, which brings the total to about 7.9 million square kilometers. The country has 54,716 kilometers of coastline and 2,958 kilometers of land boundaries with borders of 253 kilometers with East Timor, 1,881 kilometers with Malaysia and 824 kilometers with Papua New Guinea. Elevation extremes: lowest point: Indian Ocean 0 meters; highest point: Puncak Jaya 4,884 meters in Papua Province in New Guinea.

Most of Indonesia is coastal lowlands, with the larger islands having interior mountains .About 12.34 percent of the country is good for agriculture (compared to 21 percent in the U.S.) and most of this arable land is located on Java, Sumatra, Sulawesi and the islands of Nusa Tengarra. Land use: permanent crops: 10.5 percent; other: 77.16 percent (2011). Irrigated land: 67,220 square kilometers (2005). About 50 percent of Indonesia’s land is covered by rain forest (down from nearly 90 percent 60 years ago), most of it in Sumatra, Kalimantan, Papua and Sulawesi. Indonesia’s rainy, humid, tropical climate is ideal for rain forests but the amount of forest get smaller everyday as lumber companies, slash-and-burn farmers and palm oil and coffee plantation owners cut down these forests. The east coast of Sumatra, the southern coast of Kalimantan and Papua and much of the northern coast of Java is covered by marshes, swamps and mangrove forests.

Land Use and Where People Live in Indonesia

Land use: agricultural land: 29.1 percent (2023 estimate); arable land: 9.4 percent (2023 estimate); permanent crops: 13.9 percent (2023 estimate); permanent pasture: 5.8 percent (2023 estimate); forest: 50.6 percent (2023 estimate); other: 20.3 percent (2023 estimate). Arable land is land cultivated for crops like wheat, maize, and rice that are replanted after each harvest. Permanent crops is land cultivated for crops like fruit trees oranges that are not replanted after each harvest. Irrigated land: 67,220 square kilometers (2012). [Source: CIA World Factbook]

map of Indonesia

Population distribution: The population of Indonesia is concentrated on a few islands.There are major concentration of people on the island of Java, which is considered one of the most densely populated places on earth;. Of the outer islands, Sumatra contains some of the most significant clusters, particularly in the south near the Selat Sunda and along the northeastern coast near Medan. The cities of Makasar (Sulawesi), Banjarmasin (Kalimantan) are also heavily populated. [Source: CIA World Factbook]

Around 50 per cent of Indonesians live on Java, Madura and Bali, which together account for just 7 per cent of the country's land. By contrast, Papua is home to just 1 percent of the population despite covering 22 percent of Indonesia's land. These disparities have led to severe ethnic conflict, particularly when the Indonesian government's "transmigration" programme resettled people from densely populated islands to less populated provinces, such as Kalimantan and Papua. [Source: Geo-Data: The World Geographical Encyclopedia, Gale Group Inc., 2003]

The fact that there are so many islands and so much water and the islands are often mountainous and covered by dense forest has traditionally hindered transportation and communication and helps explain why Indonesia boast so many different ethnic groups. Indonesia's variations in culture have been shaped — although not specifically determined — by centuries of complex interactions with the physical environment. Although Indonesians are now less vulnerable to the vicissitudes of nature as a result of improved technology and social programs, to some extent their social diversity has emerged from traditionally different patterns of adjustment to their physical circumstances.[Source: Library of Congress]

Major Cities: (estimated population in 2013 and 1991): Jakarta (the capital) 9,770,000 and 8,300,000; Surabaya (Java), 2,880,000 and 2,400,000; Bandung (Java), 2,430,000 and 2,000,000; and Medan, 2,120,000 and 1,700,000 (Sumatra); Semarang (2013), 1,570,000; Palembang 1,460,000; Ujuung Padang, 1,390,000; and Batam, 1,035,000

Geology of Indonesia

Indonesia lies in the Ring of Fire and is one the most volcanically active and earthquake prone areas on earth. The islands in Indonesia were created mostly by volcanic activity and ocean mountain-building activity created by the movement of tectonic plates in Asia, the Indian Ocean and the Pacific Ocean. In the area of Indonesia, two large plates—the Indian Ocean and western Pacific plates—slide under an even more massive plate—the Eurasian plate—and the Eurasian and Australian continental plates collide. Tectonically, this region — especially Java — is highly unstable, and although the volcanic ash has resulted in fertile soils, it makes agricultural conditions unpredictable in some areas. The country has numerous mountains and some 400 volcanoes, of which approximately 100 are active. Indonesia was forced up from geological plates from Australia, Asia and the Pacific. A deep trench runs along the southern coast of the Indonesian chain.

map of Indonesia

The collision of the Eurasian and Australian continental plates form a subduction zone that produces numerous earthquakes and a chain of volcanoes that runs from Sumatra through Java to New Guinea with a a few side branches to Sulawesi and the Molluccas. At subduction zones two plates collide head on, with one plate going over the top, forcing the other one down. In some cases the motion produces a descending convection current that sucks down the ocean floor. In these places deep seas trenches form; mountain building activity and earthquakes occur; and millions of tons of rock sink into the crust everyday. Subduction faults are usually angled at about 10 to 15 percent and often located where major oceans and continents meet. Where ocean crust, pushed down by the weigh of ocean water, is shoved under the thick crust of continents, the rock is heated, causing water and gases to bubble out. As they rise they melt the rock above it, creating magma that can fuel volcanoes.

Geographers believe that the island of New Guinea, of which Papua is a part, may once have been part of the Australian continent. The breakup and tectonic action created both towering, snowcapped mountain peaks lining its central east-west spine and hot, humid alluvial plains along the coast of New Guinea. Papua's mountains range some 650 kilometers east to west, dividing the province between north and south. [Source: Library of Congress]

The mountains of Indonesia are underwater mountain ranges that rise above sea level to form islands. During earlier geological periods, the eastern and south-eastern regions of Asia underwent several stages of folding, the evidence of which can be seen in the two long mountain systems that intersect in the eastern Indonesian islands of Sulawesi (Celebes) and Halmahera. The first system consists of two parallel ridges that continue the western Burmese chain. It runs through Sumatra, Java, Bali and Timor, curving sharply in a great hook through the southeastern islands to Ceram and Buru. The second system runs southwest through the Philippines into eastern Indonesia, which explains the complexity of the mountain structure and the peculiar shape of Sulawesi and Halmahera, where ranges run in both north-south and east-west directions. Sulawesi is extremely mountainous, with peaks rising to over 2,438 metres (8,000 feet) in places. [Source: Geo-Data: The World Geographical Encyclopedia, Gale Group Inc., 2003]

People and Land in Indonesia

Jill Forshee wrote in “Culture and Customs of Indonesia”: In Indonesia, “People maximized many different ecological conditions, creating complementary needs and interests between groups. Thus, necessities of reciprocal trade and services between highland peoples with those of coastal regions, and between swidden and wet-rice agriculturalists, established interdependant economies. For example, inland peoples might trade wood products, crafts, or garden produce for ﬁsh, salt, and imported goods from port communities. Indonesia is a hot, equatorial land, becoming chilly at high altitudes. Snow falls only in West Papua around the mountain Puncak Jaya (16,503 ft.), which contains permanent glaciers. [Source:Jill Forshee, “Culture and Customs of Indonesia”, Greenwood Press, 2006]

20120515-Crop harvest in Indonesia.jpg
Crop harvest in Indonesia Water deﬁnes Indonesia as much as does land—to the extent that Indonesians refer to their nation as tanah air, meaning “land and water.” In a vast region of long maritime commerce and sustenance, oceans deﬁne the archipelago as essentially as land in terms of human environments and resources. The ubiquitous Indonesian seas abound in life supporting ﬁshing communities. In fact, some ﬁsherfolk, such as those from the Sulu Islands between the Philippines and Sulawesi, live on boats all year. Floating communities of people animate the waters of some regions, regarding the sea as home and the land as a place for trade, not settlement.

“Human impacts upon the land, such as wet-rice and swidden (slashand-burn) agriculture, reconﬁgured regions of Indonesia drastically. Wet-rice agriculture versus swidden methods form a classic distinction between geographical regions for scholars—contrasting the “Inner Indonesia” of Bali and Java and the “Outer Indonesia” of all other islands. People in heavily forested regions such as Kalimantan or West Irian practice a slash-and-burn type of agriculture called ladang. These clearings cut from forests support crops for two to three years, until exhausting soil nutrients. Then people clear a new ladang. When farmed on a small scale, slash-andburn regions recover their original growth to a good degree. This type of cultivation does not permit the population density of wet-rice agricultural communities. Swidden settlements require about ten times the land that they actually cultivate in a year.

As people must walk long distances to their ﬁelds, villages normally number a few hundred people, often living at some distance from each other. Historically, these were fairly egalitarian societies, with no place for kings. Swidden agriculturalists practiced animism, centering on their plants, water, and ancestors. They based beliefs in complex perceptions of natural and supernatural realms. Bali presents a marvel of cultivation through an intricate environment of rice terraces, as water systems intrinsically sculpt much of the island. Moreover, the elaborate irrigation systems required for wet-rice agriculture (called sawah) are only possible through organized communities built upon social cooperation. In Bali, subaks form such communal systems involving people in associations for all aspects of maintaining extensively irrigated rice paddies.

Boundary and Territorial Issues Involving Indonesia

Indonesia shares parts of Borneo with Malaysia and Brunei and parts of the province of Papua (located on the island of New Guinea and formerly known as Irian Jaya) with Papua New Guinea. Indonesia disputes ownership of Sipadan and Ligitan Islands off the east coast of Borneo with Malaysia. [Source: Junior Worldmark Encyclopedia of Physical Geography, Gale Group, Inc., 2003]

The legal rights to, and responsibility for, Indonesia’s territorial environment are a matter of controversy. Among the continuing concerns are the exact boundaries between Indonesia and Timor-Leste; another issue of concern between the two states is sovereignty over a tiny uninhabited island off the coast of Timor that is called Pulau Batek by Indonesia but known locally as Fatu Sinai. Differences over the precise maritime boundaries between Australia and Indonesia in the Timor Gap remain an area in need of reconciliation. [Source: Library of Congress *]

In another dispute, the International Court of Justice ruled in favor of Malaysia in 2002 regarding jurisdiction over the Sipadan and Ligitan islands (off northeastern Kalimantan). However, Indonesia continues to assert a claim to the outer islands of the Ligitan group and has established a presence on them. In 2005 tensions flared again between Indonesia and Malaysia concerning Ambalat Island, located in the Sulawesi Sea (Celebes Sea) on the boundary between the two states, off the northeast corner of Kalimantan Timur Province. *

Basing its claim on a doctrine of the political and security unity of archipelagic land and waters (wawasan nusantara), the Indonesian government has asserted its rights to marine and geologic resources within a coastal zone of 200 nautical miles. Indonesia, Malaysia, and Singapore each consider the Strait of Malacca (Selat Malaka in Bahasa Indonesia), one of the most heavily traveled sea-lanes in the world, to be their primary responsibility. At a conference in Singapore in 2004, the United States recognized the right of the three countries to organize security as they saw fit, while at the same time offering assistance for their efforts. *

Since the late 1990s, Indonesia has experienced major challenges to its territorial integrity. The most profound resulted from a United Nations (UN)–monitored referendum in August 1999 in East Timor on whether to accept special autonomy within Indonesia or to separate from Indonesia and declare independence. After 78.5 percent of East Timorese voted for independence, pro-Indonesia and pro-independence forces fought each other, and thousands died or fled to West Timor (Nusa Tenggara Timur Province) to avoid the fighting. The violence began shortly after President Bacharuddin J. (B. J.) Habibie announced the referendum and continued until well after the vote. On October 25, 1999, the UN Transitional Administration in East Timor (UNTAET) was established, and on May 20, 2002, East Timor, as the Democratic Republic of Timor- Leste, became fully independent of Indonesia. Most of the estimated 200,000 refugees who went to West Timor had returned by 2003.

Another dispute has involved Indonesia's conflict with Australia over rights to the continental shelf off the coast of Timor. This problem was resolved in 1991 by a bilateral agreement calling for joint economic exploitation of the disputed area in the so-called "Timor Gap." Still other controversies arose regarding overflight rights in Papua (disputed with Papua New Guinea) and conflicting claims to the Spratly Islands in the South China Sea by Brunei, China, Malaysia, the Philippines, Taiwan, and Vietnam. Indonesia played the role of mediator in the Spratly Islands controversy. [Library of Congress]

Trouble Spots in Indonesia: Aceh and Papua

Two other regional struggles in recent times were in the Special Region of Aceh, in northwestern Sumatra, and in Papua. In Aceh, the long-standing conflict between the Free Aceh Movement and the Indonesian military intensified into an open secessionist effort. The struggle escalated in 1998, but two years later secret negotiations held in Geneva led to a Cessation of Hostilities Agreement signed on December 9, 2002. The parties had agreed to a dialogue leading to democratic elections and a cessation of hostilities. Within six months, however, the agreement had broken down, and martial law was declared in the province until May 2004.

Following the December 2004 earthquake and tsunami, a much more comprehensive peace agreement, brokered by former Finnish president Martti Ahtisaari, was officially signed in Helsinki on August 15, 2005, by chief Indonesian negotiator Hamid Awaluddin and GAM leader Malik Mahmud. The Indonesian government agreed to facilitate the establishment of Aceh-based political parties and to allow 70 percent of the income from local natural resources to stay within Aceh. On December 27, 2005, GAM leaders announced that they had disbanded their military wing and GAM itself was dissolved the next month.

Another important challenge to Indonesia’s sovereignty comes from the Free Papua Organization (OPM). After years of sabotage, secret meetings, and public demonstrations, OPM gained considerable international attention in January 1996 when members of the group kidnapped 14 members of a multinational World Wildlife Fund for Nature scientific expedition. All except two hostages were freed following negotiations; later a rescue operation was conducted in which six OPM members and the two remaining Indonesian hostages were killed. Although in 2001 local leaders were granted more financial and political autonomy and had been permitted a year earlier to change the name of their province from Papua to the locally more acceptable Papua, tension persists. (In 2003 Papua was subdivided into Papua and Papua Barat provinces; the latter was renamed Papua Barat in 2007.)

Amnesty International reported grave concern about acts of torture and prisoner abuse in 2000 by the Indonesian military. Demonstrations for Papuan independence intensified in 2006 in the wake of revelations of pollution caused by the Grasberg mine, a source of copper, gold, and silver operated by Phoenix, Arizona–based Freeport-McMoRan Copper and Gold. In 2008 Indonesian police arrested separatist leader Buchtar Tabuni as he was about to attend a massive rally in Jayapura, the capital of Papua, to show support for an international legislative caucus for Papua Barat. [Library of Congress]

Image Sources: Wikimedia Commons

Text Sources: “Encyclopedia of World Cultures Volume 5: East/Southeast Asia:” edited by Paul Hockings, 1993; “Culture and Customs of Indonesia” by Jill Forshee, Greenwood Press, 2006; National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Encyclopedia.com, Library of Congress, Indonesia Tourism website (indonesia.travel), Indonesia government websites, Live Science, The Conversation, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Google AI, Wikipedia, The Guardian and various websites, books and other publications.

Last updated June 2026