The longest axis of the island runs approximately northwest – southeast, crossing the equator near the center. The interior of the island is dominated by two geographical regions: the Barisan Mountains in the west and swampy plains in the east. To the southeast is Java, separated by the Sunda Strait. To the north is the Malay Peninsula, separated by the Straits of Malacca. To the east is Borneo, across the Karimata Strait. West of the island is the Indian Ocean.
The backbone of the island is the Barisan mountains chain. The volcanic activity of this region endowed the region with fertile land and beautiful sceneries, for instance around the Lake Toba. It also contains deposits of coal and gold.To the east, big rivers carry silt from the mountain, forming the vast lowland interspersed by swamps. Even if mostly unsuitable for farming, the area is currently of great economic importance for Indonesia. It produces oil “from above the soil and underneath”, the palm oil and petroleum. Most of Sumatra used to be covered by tropical rainforest, home to species such as orangutans, tapirs, and Sumatran tigers, and some unique plants like the Rafflesia. Unfortunately, economic development coupled with corruption and illegal logging has severely threatened its existence. Conservation areas have not been spared from destruction, either.
Sumatra supports a wide range of vegetation types which are home to a rich variety of species, including 17 endemic genera of plants. Unique species include: Sumatran Pine, Rafflesia arnoldii (world’s largest individual flower), Titan arum (world’s tallest and largest inflorescence flower).
The island is home to 201 mammal species and 580 bird species. There are 9 endemic mammal species on mainland Sumatra and 14 more endemic to the nearby Mentawai Islands. The species present include: Sumatran Tiger, Sumatran Orangutan, Sumatran Rhinoceros, Sumatran Elephant, Sumatran Striped Rabbit, Dhole, Dayak Fruit Bat, Malayan Tapir, Malayan Sun Bear and the Bornean Clouded Leopard. The major threats to Sumatran forest are the pulp and paper industry and expansion of palm oil plantations. The island includes more than 10 National Parks, including 3 which are listed as the Tropical Rainforest Heritage of Sumatra World Heritage Site Gunung Leuser National Park, Kerinci Seblat National Park and Bukit Barisan Selatan National Park.
Sumatra is not very densely populated, about 85 people per sq.km (with more than 40 million people in an area the size of Germany). It is nonetheless the fifth most populous island in the world. The most populous regions includes most of Sumatra Utara and central highland in Sumatra Barat, while the major urban centre are Medan and Palembang.
The people are of Malay stock composed of many different tribes, speaking 52 different languages. Most of these groups, however, share many similar traditions and the different tongues are closely related. Malay-speaking people dominate the eastern coast, while people in the southern and central interior speak languages related to Malay, such as Lampung and Minangkabau. The highland of northern Sumatra is inhabited by the Bataks, while the northernmost coast is dominated by Acehs. Ethnic Chinese minorities are also present in urban centers.
A majority of people in Sumatra are Muslims. Most central Bataks, meanwhile, are Protestant Christians – the religion was spread by the Dutch. The rest follow Hinduism, Buddhism, Catholicism, and Chinese traditional beliefs.
Sitting astride the equator, Sumatra’s climate is about as tropical as gets. Daytime temperatures seldom fail to reach 30°C (86°F) on the coast, but fortunately the weather is appreciably cooler inland around the mountains. Places like Berastagi, Bukittinggi and Danau Toba get cool enough at night to warrant a blanket. The dry season runs from May to September. The timing of the wet season is hard to predict. In the north, the rains start in October, and December/January are the wettest months; in the south, the rains start in November, peaking in January/February. Bengkulu and West Sumatra are the wettest places, with average rainfall approaching 3500mm.
How to get there
Most travellers arrive and depart through Medan by air-flight. You can fly from Jakarta to a number of places in Sumatra, and from Singapore, Penang and Kuala Lumpur to Medan. International flights from Singapore and Kuala Lumpur touch down in Padang.
There are ferries between Penang and Medan; Melaka and Dumai; and Singapore and Pekanbaru via the Indonesian island of Bintan.
Best time to travel
The dry season is the best time of year to visit Sumatra which starts in May and ends September. The best months are June and July. The wet season starts in September with regular afternoon showers and progresses through to Jan/Feb with longer periods of rain.