The clouded leopard (Neofelis nebulosa), also called mainland clouded leopard, is a wild cat that has large dusky-grey blotches and irregular spots and stripes reminiscent of clouds. Its head-and-body length ranges from 68.6 to 108 cm (27.0 to 42.5 in) with a 61 to 91 cm (24 to 36 in) long tail, which it uses for balancing when moving in trees.

Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. In 1996, they were divided into two species: the Bornean orangutan (P. pygmaeus, with three subspecies) and the Sumatran orangutan (P. abelii); a third species, the Tapanuli orangutan (P. tapanuliensis), was identified definitively in 2017.

Borneo (/ˈbɔːrnioʊ/) is the third-largest island in the world, with an area of 748,168 km2 (288,869 sq mi), and population of 23,053,723 (2020 national censuses).[1][2][3] Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda Islands, located north of Java, west of Sulawesi, and east of Sumatra. The island is crossed by the equator, which divides it roughly in half. In Indonesia, the island is also known as Kalimantan.

Deer Cave (Malay: Gua Rusa), located near Miri, Sarawak, Malaysia, is a show cave attraction of Gunung Mulu National Park. It was surveyed in 1961 by G. E. Wilford of the British Borneo Geological Survey, who predicted that Mulu would yield many more caves in the future.[3] The cave, which is also known as Gua Payau or Gua Rusa by the local Penan and Berawan people, is said to have received its name because of the deer that go there to lick salt-bearing rocks[4] and shelter themselves.