Where Are Java and Sumatra? (Indonesia's Two Largest Islands)

Both are major islands in the Indonesian archipelago, part of the Greater Sunda Islands in Southeast Asia.

Java (Pulau Jawa)

• Position: South of the South China Sea, north of the Indian Ocean, between Sumatra (west) and Bali (east).
• Area: 129,904 km² (50,156 sq mi) — world's 13th largest island.
• Population: ~152 million (2023) — most populous island on Earth (56% of Indonesia's people).
• Capital: Jakarta (northwest coast) — Indonesia's capital and largest metro (~34M).
• Key cities: Surabaya, Bandung, Semarang, Yogyakarta, Solo.
• Geography: Volcanic spine (38+ active volcanoes), fertile plains, dense population.

Sumatra (Pulau Sumatera)

• Position: Northwest of Java, across the Sunda Strait. Straddles the equator. West: Indian Ocean; East: Strait of Malacca.
• Area: 473,481 km² (182,812 sq mi) — 6th largest island globally, largest entirely in Indonesia.
• Population: ~59 million (2023).
• Major city: Medan (north) — largest outside Java (~4.5M metro).
• Other cities: Palembang, Pekanbaru, Padang, Banda Aceh, Lampung.
• Geography: Bukit Barisan volcanic range (west), vast eastern lowland swamps/rainforest, Lake Toba (supervolcano caldera).

Strategic Importance

• Strait of Malacca (Sumatra's northeast) — 25% of global maritime trade passes here.
• Sunda Strait (between Sumatra & Java) — key alternate route; Krakatoa volcano.
• Both islands produce: oil, gas, coal, tin, rubber, palm oil, coffee, tea.

Memory aid: Java = people + volcanoes + capital. Sumatra = size + resources + equator + Malacca Strait.