Sumatra: Size, Geography, and Significance of Indonesia's Largest Island

Sumatra is the sixth-largest island in the world and the largest island entirely within Indonesia (Borneo and New Guinea are shared).

Key Statistics

• Area: ~473,481 km² (182,812 sq mi) — slightly larger than California or Sweden.
• Dimensions: ~1,790 km (1,110 mi) NW–SE × ~435 km (270 mi) max width.
• Population: ~58–60 million (2023 est.) — 4th most populous island globally (after Java, Honshu, Great Britain). Density: ~125/km².
• Largest City: Medan (metro ~5 million) — North Sumatra's commercial hub.
• Highest Point: Mount Kerinci (3,805 m / 12,484 ft) — highest volcano in Indonesia, in Kerinci Seblat National Park.

Geography & Ecology

• Barisan Mountains: Volcanic spine running the island's length — 35+ active volcanoes, crater lakes (Lake Toba — world's largest volcanic lake, 1,145 km²).
• East Coast Lowlands: Swampy, wide rivers (Musi, Batanghari, Kampar), vast palm oil/rubber plantations, mangroves.
• Rainforests: Among Earth's most biodiverse. UNESCO Tropical Rainforest Heritage of Sumatra (Gunung Leuser, Kerinci Seblat, Bukit Barisan Selatan NPs).
• Iconic Wildlife: Critically endangered Sumatran orangutan, tiger, elephant, rhino (all endemic subspecies). Also sun bear, tapir, siamang.

Economy & Resources

• Oil & Gas: Major fields (Riau, South Sumatra) — Indonesia's historic petroleum heartland.
• Palm Oil: World's largest producer (controversial: deforestation, haze).
• Rubber, Coffee, Tea, Pepper, Coal, Tin, Gold.
• LNG Export: Tangguh, Arun (Aceh).

People & Culture

• Ethnic Groups: Acehnese, Batak (Toba, Karo, etc.), Minangkabau (matrilineal), Malay, Rejang, Lampung, Nias, Mentawai, Kubu (Orang Rimba).
• Religion: Majority Muslim (Shafi'i), except Batak (Christian), Mentawai (animist/Christian), some Hindu/Buddhist minorities.
• Matrilineal Minangkabau: World's largest matrilineal society — property/name pass through mothers.

Challenges

Deforestation (palm oil, pulp, mining, illegal logging), peatland fires/haze, human-wildlife conflict, earthquake/tsunami risk (2004 Aceh), separatist history (Aceh - resolved 2005), infrastructure gaps.