Borneo, the third largest island in the world, divided between Indonesia, Malaysia and Brunei, was once covered with dense rainforests, but along with its tropical lowland and highland forests, there has been extensive deforestation in the past sixty years^[clarify]. In the 1980s and 1990s the forests of Borneo underwent a dramatic transition. They were levelled at a rate unparalleled in human history, burned, logged and cleared, and commonly replaced with agricultural land, or palm oil plantations. Half of the annual global tropical timber acquisition currently comes from Borneo. Furthermore, palm oil plantations are rapidly encroaching on the last remnants of primary rainforest. Much of the forest clearance is illegal.

The World Wildlife Fund divides Borneo into a number of distinct ecoregions including the Borneo lowland rain forests which cover most of the island, with an area of 427,500 square kilometres (165,100 sq mi), the Borneo peat swamp forests, the Kerangas or Sundaland heath forests, the Southwest Borneo freshwater swamp forests, and the Sunda Shelf mangroves. The Borneo mountain rainforests lie in the central highlands of the island, above the 1,000 metres (3,300 ft) elevation. These areas represent habitat for many endangered species, such as orangutans and elephants and rare endemics such as the elusive Hose's Civet.