Indonesia Map

An archipelago between two continents

Indonesia stretches more than 5,000 kilometers from Sabang off northern Sumatra to Merauke in Papua, across three time zones (UTC+7 to UTC+9). Official island counts have ranged from about 17,000 to 17,508 depending on the survey and the definition used. Five large land masses dominate the map: Sumatra; Java; Kalimantan, the Indonesian part of Borneo, shared with Malaysia and Brunei; Sulawesi; and the western half of New Guinea, shared with Papua New Guinea. Between them lie the Lesser Sunda chain (Bali, Lombok, Sumbawa, Flores, Sumba and western Timor) and the Maluku islands, the original Spice Islands. The land area of about 1.9 million square kilometers is the largest in Southeast Asia, and the population of about 286 million (UN World Population Prospects, 2025 estimate) is the world's fourth largest. Java alone, roughly the size of England, holds more than half of all Indonesians.

Between Bali and Lombok, and between Borneo and Sulawesi, runs the Wallace Line, the boundary between Asian and Australasian wildlife: orangutans and Sumatran tigers live to the west of it, and marsupials such as cuscuses and tree kangaroos, along with birds of paradise, to the east. Komodo dragons survive only on Komodo, Rinca and nearby parts of Flores.

Volcanoes and the highest peaks

Indonesia sits where the Indo-Australian, Eurasian and Pacific plates meet, and the Sunda Arc of volcanoes runs the length of Sumatra, Java, Bali and the Lesser Sundas before curving through the Banda Sea. The national volcanology agency monitors about 127 active volcanoes. The 1815 eruption of Tambora on Sumbawa was the most powerful in recorded history and caused the "year without a summer" in 1816, and the 1883 eruption of Krakatau in the Sunda Strait was heard thousands of kilometers away. Lake Toba in North Sumatra fills the caldera of a supervolcano that erupted about 74,000 years ago and is the largest volcanic lake in the world. Rich volcanic soils around peaks such as Merapi near Yogyakarta and Bromo in East Java help explain why Java can feed so many people. The highest point is not a volcano: Puncak Jaya (Carstensz Pyramid), 4,884 meters, in the Sudirman Range of Papua, is the highest island summit on Earth and one of the last places near the equator with glacier ice, which is fast disappearing (see mountain ranges of Asia).

Dry season, wet season

The lowlands are hot and humid all year, so seasons are about rain. On Java, Bali, Lombok and the Lesser Sundas the dry season runs roughly from May to September and the wet season from November to March, which makes April to October the best time for Bali, Lombok or Komodo; the islands east of Bali are the driest part of the country. Sumatra and Kalimantan, closer to the equator, get heavy rain in most months, and Maluku is the exception, with its rainiest months around June to August. Typhoons do not reach most of Indonesia, but peat and forest fires in dry years, especially during El Niño, can spread haze to Singapore and Malaysia.

Provinces and the capital question

Indonesia has 38 provinces. The latest four were created in 2022, when Papua was split into Papua, South Papua, Central Papua and Highland Papua and Southwest Papua was carved out of West Papua. Aceh has special autonomy and applies sharia-based bylaws, and Yogyakarta is the only province still headed by a hereditary sultan as governor.

Jakarta, on the northwest coast of Java, remains the capital and the seat of the president, parliament and ministries. A 2022 law designated Nusantara (Ibu Kota Nusantara, or IKN), a new city being built in East Kalimantan on Borneo, as the future capital, partly because Jakarta is congested and parts of its coast are sinking. The presidential palace there hosted the Independence Day ceremony in 2024, but the law makes the transfer effective only once the president issues a decree, and in May 2026 the Constitutional Court confirmed that Jakarta keeps its capital status until then. A 2025 presidential regulation sets the goal of making Nusantara the "political capital" by 2028. As of 2026 about 2,000 civil servants were working there, construction of buildings for parliament and the courts was under way, and the project was behind its original schedule, with less private investment than planned.

Major cities

• Jakarta - the Special Region of Jakarta has more than 10 million residents, and the wider urban area, which spreads into Bogor, Depok, Tangerang and Bekasi, was ranked the world's most populous city, with nearly 42 million people, in the UN's World Urbanization Prospects 2025. It also hosts the ASEAN Secretariat.
• Surabaya - Indonesia's second city and the main port of East Java; the battle fought there in November 1945 is remembered every 10 November as Heroes' Day.
• Bandung - a university and textile city in the cool highlands of West Java, and host of the 1955 Asian-African Conference that helped launch the Non-Aligned Movement.
• Medan - the largest city on Sumatra, the commercial hub of the North Sumatra plantation belt and the usual gateway to Lake Toba.
• Makassar - the main city of Sulawesi and a hub for shipping and flights to eastern Indonesia.
• Yogyakarta - Java's best-known cultural center and a living sultanate, close to Borobudur, the world's largest Buddhist temple, built in the 9th century, and the Hindu temples of Prambanan.

History that drew the borders

Srivijaya on Sumatra and Majapahit on Java were the great maritime powers before Islam spread along the trade routes from the 13th century. Today about 87% of Indonesians are Muslim, the largest Muslim population of any country, while Bali is mostly Hindu and parts of the east are mainly Christian. The Dutch East India Company seized Jakarta, which it renamed Batavia, in 1619, and Dutch control spread across the archipelago until the early 20th century; those colonial limits became Indonesia's borders. Sukarno and Hatta proclaimed independence on 17 August 1945, and the Netherlands transferred sovereignty in December 1949 after four years of fighting and negotiation. Western New Guinea came under Indonesian administration in 1963 and was formally incorporated after the contested 1969 Act of Free Choice. Indonesia occupied East Timor in 1975; the territory voted for independence in 1999 and is now Timor-Leste.

Indonesia was a founding member of ASEAN in 1967, is the bloc's largest economy and joined BRICS in January 2025. It supplies more than half of the world's palm oil and is a leading exporter of coal and nickel. Bahasa Indonesia, a standardised form of Malay, is the national language, alongside hundreds of regional languages such as Javanese and Sundanese. At sea, its neighbours include Singapore and Malaysia across the Singapore and Malacca straits, the Philippines, Palau and Australia. China's claim in the South China Sea overlaps part of Indonesia's exclusive economic zone north of the Natuna Islands, which Indonesia does not regard as a territorial dispute.