Borneo Rainforest

The Borneo Rainforest covers most of the huge tropical island of Borneo in Southeast Asia. The island is shared by three countries: Indonesia, Malaysia and the tiny nation of Brunei. The Borneo Rainforest is one of the oldest on Earth (approx. 140 million years old, twice as old as the Amazon) and the only home of the Bornean orangutan.

• Areaapprox. 290,000 km²Across the island of Borneo
• CountriesIndonesia, Malaysia, BruneiBorneo is split between all three
• Ageapprox. 140 million yearsAbout twice as old as the Amazon
• Famous animalBornean orangutanLives only here
• Other animalsPygmy elephantsPlus proboscis monkeys and sun bears
• Biggest threatPalm oil farmingAbout half the forest already cleared

How big is the Borneo Rainforest?

Area (million km²)

Amazon5.5

Congo2.0

Sundaland1.0

Borneoapprox. 0.29

Borneo is part of the larger Sundaland rainforest region, which once stretched across many of the islands of Southeast Asia.

What is the Borneo Rainforest?

Borneo is the third biggest island in the world. Most of it used to be covered in dense tropical rainforest. About half of that forest has now been cleared, but huge areas remain, especially in the interior mountains. The rainforest is incredibly rich in life, with new species still being discovered all the time. More than 200 new species were found in Borneo between 2010 and 2020 alone.

The Bornean orangutan

The orangutan is one of our closest cousins, sharing approx. 97% of its DNA with humans. The name means "person of the forest" in Malay. Adult males can weigh 90 kg and have arm spans of over 2 metres. They spend almost their entire lives in the trees and rarely come down to the ground.

The Bornean orangutan is found only on this island. Its numbers have crashed from over 230,000 in the 1970s to just over 100,000 today, due to loss of forest. Orangutans are highly intelligent and have been seen using tools, learning sign language, and even sharing food with strangers.

Fact Borneo is home to the world's biggest flower, the Rafflesia. It can grow up to a metre across and weighs around 7 kg. It also smells like rotting meat, which is why it is sometimes called the corpse flower.

Other amazing wildlife

Borneo is home to over 200 species of mammal, 600 species of bird, and 15,000 species of plant. Famous residents include the pygmy elephant (the smallest elephant in the world, found only on the north of the island), the proboscis monkey (with a huge floppy nose), the Sumatran rhino (one of the rarest large animals on Earth), the clouded leopard, the slow loris and the sun bear.

The palm oil crisis

The biggest threat to the Borneo Rainforest is palm oil farming. Palm oil is a cheap vegetable oil used in about half of all supermarket products, from chocolate to soap to fuel. To grow it, huge areas of rainforest are burned and replaced with palm plantations. Borneo has lost about half of its original forest cover, mostly to palm oil. The fires used to clear the land also release vast clouds of smoke that have darkened skies across Southeast Asia.

Did you know? The orangutan baby stays with its mother for around 7 years, learning what is safe to eat in the rainforest. That is the longest childhood of any wild mammal apart from humans.

Deeper dive: Borneo geology, peat fires and Bornean conservation

Borneo sits on the Sunda Shelf, a section of continental crust that was connected to mainland Southeast Asia during the last ice age. As sea levels rose at the end of the ice age, around 10,000 years ago, the shelf was flooded and the islands of Sumatra, Java and Borneo were cut off. This relatively recent isolation means the wildlife of Borneo is closely related to that of mainland Asia, but with many endemic (found nowhere else) species that have evolved since.

Much of the Bornean lowland forest grows on a layer of peat, partially decomposed plant material that can be metres thick. When this peat dries out (often deliberately by drainage for palm oil plantations) it becomes highly flammable. The 2015 Indonesian peat fires were among the most polluting events in recent history, blanketing Southeast Asia in a haze that closed schools and airports as far away as Singapore and southern Thailand. The fires released roughly the same amount of CO₂ as Germany emits in a year, in a single fire season.

Conservation in Borneo is complicated by being shared between three countries with different governments and priorities. The Heart of Borneo initiative, launched in 2007, aims to protect a 220,000 square km area across all three nations as a continuous conservation zone. Successful programmes include the orangutan rescue centres of Sepilok and Nyaru Menteng, where orphaned orangutans (often whose mothers were killed in palm-oil clearance) are reared and eventually released back into protected forest. The eco-tourism industry in Sabah (Malaysian Borneo) has also become an important economic alternative to logging and palm oil for many local communities.

For the biggest rainforest of all, see the Amazon. The country with most of Borneo is Indonesia.