An Island that Erupted from the Sea

The island of Borneo started as a single volcano beneath the sea. Millions of years ago, it erupted. Over time, smaller eruptions and earthquakes joined land together to form an island. Today, Borneo is the third largest island in the world. It is twice the size of Japan. Three countries share the island: Malaysia, Indonesia, and Brunei.

Over 16 million people live on Borneo. Borneo’s landscape and wildlife are diverse and include high mountains and rugged coastlines. Most of the island is covered with dense, ancient tropical rainforest. Borneo’s rare and endangered wildlife includes the orangutan, Asian elephant, proboscis monkey, flying frog, and many species of rare plants.

Mount Kinabalu is the highest point on Borneo

Mount Kinabalu is the highest point on Borneo. It rises 4,101m above sea level and is the second highest mountain in Southeast Asia.


A Three-Nation Island

Borneo is part of a larger region called Southeast Asia. The island’s population lives in the provinces and states of the three nations that share the island. Two major ethnic groups found on Borneo are the Dayaks and the coastal Malays (MAY-lays). Kalimantan (KAH-li-man-tan) was also a center for Chinese settlement. In the past 50 years, many new immigrants have come to Borneo from other parts of Indonesia to escape overcrowding.

Indonesian Borneo

The Indonesian part of Borneo is the southern two-thirds of the island's area. It is divided into the four provinces of West, Central, South, and East Kalimantan. About 12 million people live in Kalimantan.

Malaysian Borneo

About 4 million people live along Borneo’s north coast in the two Malaysian states of Sarawak (sah-RAH-wak) and Sabah (SAH-bah).

Brunei Borneo

The Sultanate (SUL-tuhn-ate) of Brunei is an independent country. Brunei's population is 300,000.

A Remote and Rugged Landscape

Borneo’s landscape is made up of steep mountains and remote river valleys. Even today, much of Borneo is so rugged that it has not been explored. Borneo's highest point is Mount Kinabalu in the northwest region of Sabah. It has an elevation of 4,101m above sea level.

Recipe for a Tropical Rainforest

Borneo has a tropical climate. It is the location of the world’s oldest rainforest. The following “ingredients” provide the perfect conditions for the dense tropical rainforest to grow:

  • Warm, constant temperatures
  • Lots of rain
  • A variety of mountainous terrain
  • Little human disturbance

Until a few decades ago, the rainforest spread uninterrupted like a green blanket over the entire island. Some areas of Borneo receive up to 510 cm of rainfall each year. There is no true dry season. The rainy season lasts all year. The heaviest rain falls during monsoon season between October and March. The average temperature is 26 ºC.

Bursting With a Variety of Life

Hornbills are important to the tropical rainforest of Borneo.

Hornbills are important to the tropical rainforest of Borneo. Their bills help them eat large fruits and carry seeds to new areas of the forest.

Borneo’s tropical rainforest has some of the richest biodiversity on Earth. Borneo has nearly 11,000 species of flowering plants. About a third of these are indigenous. In one 6.5 hectare area of Borneo's lowland tropical rainforest, over 700 species of trees have been recorded. Few other places have this kind of variety. In England, for example, there are only 35 indigenous tree species in the whole country.

Lush Plant Growth

Vegetation is lush and varied. In the mountain regions, rhododendron, orchid, pitcher plant, and other flowering plants grow in large numbers. Native fruit trees include the coconut palm, orange, banana, and mango. The island is home to some unusual plants as well, including the world’s largest flower. It measures over 1 m across. There are also plants that eat insects and frogs!

Rare and Strange Creatures

Borneo’s rainforests are home to thousands of endemic species of animal, reptile, and insect. These include rhinos, hornbills, macaques, gibbons, tarsiers, and slow lorises. It also has some of the world’s strangest creatures, like flying lizards and frogs (they actually glide using webs of skin). New creatures are still being discovered. In 2005, for example, scientists discovered a large cat-fox mammal in Borneo’s rainforest.

Orangutans: Borneo’s Most Famous Animal

Borneo’s most famous animal is the “old man of the forest,” that is, the endangered orangutan. Over 90% of the world’s wild orangutans live on Borneo. But scientists are concerned that conservation of Borneo’s rainforest is not being taken seriously enough to save the island’s incredible diversity.

Natural Resources

Borneo has many natural resources including timber, natural gas, and oil (petroleum). Oil is the most valuable. It is found throughout the island but the largest deposits are in Brunei.

Precious Rainforests

Huge stands of old rainforest hardwood trees cover the island. The giant trees of the rainforest are called dipterocarps. More than 50 species of valuable trees grow in the tropical rainforests. Four of the most important timber trees are teak, ironwood, ebony, and sandalwood. Both Malaysia and Indonesia have been logging the trees very fast over the past 25 years.

Fire in the Forests

The tropical rainforests of Borneo are being destroyed at an alarming rate.

The tropical rainforests of Borneo are being destroyed at an alarming rate. Forests are logged and burned to make way for roads, plantations, mines, and cities. When the forests are destroyed, countless species are lost and with them Borneo’s rich biodiversity.

©F. Lanting/Minden Pictures

Forest fires have become a danger to the forests, wildlife, and people of the island. Most of these fires are the result of logging and lightning storms. Because Borneo is still very wild, once fires start they are very difficult to control. They may burn for several weeks. Some fires have become so bad that smoke will cover most of the island and even nearby areas in Java and Singapore.

Sharing the Island: Borneo's Human Population

People have lived on the island of Borneo for over 50,000 years. Four thousand years ago, more people arrived via the Malay peninsula. They settled on Borneo and other areas of Indonesia and the Philippines.

The First People

Borneo's indigenous people had a very low impact on the environment. The seas, rivers, and rainforests supplied the people with food, medicines, and building materials. These people were the ancestors to Borneo's diverse peoples that are today known collectively as Dayaks.

Endangered orangutans are one of the most recognized species of Borneo

Endangered orangutans are one of the most recognized species of Borneo. Orang utan is a local word that means “old man of the forest.”


Each Dayak society developed in its own environment. For example, coastal Dayaks were fishermen. Their neighbors in the rainforest grew small plots of plants for food. But most of their food came from hunting animals and gathering plants from the rainforest.

Europeans Stake Their Claim

Starting about 400 years ago Spanish, Portuguese, and Dutch explorers set up colonies on Borneo. They began controlling the northern coast of the island. By the 1800’s, the British controlled the area now known as Brunei, Sarawak, and Sabah. The Dutch remained in control of the southern section of the island. But much of the island remained unexplored. European explorers did not enter the dense rainforest.

Fighting Breaks Out

Over the last 400 years, many countries have argued over the ownership of Borneo. In the early 1960’s, Indonesia and Malaysia went to war over who would own the island. In 1966, after three years of fighting, the nations signed a peace treaty. The island was divided into the sections that exist today. In 1984, Brunei became an independent country.

Dramatic Developments

Much of Borneo is still covered in tropical rainforest.

Much of Borneo is still covered in tropical rainforest. The tropical rainforest provides important habitat for many unique species. Ninety percent of the world’s wild orangutans live in the rainforest of Borneo.


Borneo’s hilly terrain, rivers, and thick forests have made it difficult to develop until recently. But in the late 1940’s, machines, trucks, and chainsaws were brought to Borneo. These made it possible for settlers from the coastal areas to cut their way into the interior of the island.

Disappearing Forests, Disappearing Ways of Life

With this new exploration came an increase in industrial logging. People also began planting African oil palm plantations. These developments did not take into consideration the Dayak people. The Dayaks were forced deeper into the forest to survive. Today, most Dayaks live in villages that are connected by roads or rivers to the outside world. Some Dayaks still hunt in the forest for animals and plants. But their traditional way of life is disappearing very fast, as is the rainforest they live in.

The Iban are one of the native cultures still living in the rainforests of Borneo.

The Iban are one of the native cultures still living in the rainforests of Borneo. The Iban maintain their traditional way of life.