The Niah National Park is world famous for the oldest human remains in South-East Asia found in its Great Caves dating back some 40,000 years. The archeologists also found fragments of pottery, stone tools, ornaments and a splendid set of wall paintings of red haematite depicting activities of stick-like men with hunting weapons and boats. The works of the unknown artist is estimated to be 1000 years old.

The National Park primarily comprises alluvial or peat swamps as well as some mixed dipterocarp forest, which has several jungle tracks. Long-tailed macaques, hornbills, squirrels, flying lizards and crocodiles have been recorded in the park. There are also bat hawks, providing an impressive spectacle when they home in on one of the millions of bats, which pour out of the caves at dusk.

Millions of bats and swiftets make the dark recesses of the Niah Caves their home. Along the way, a common scene is meeting workers collecting guano, the accumulation of bird and bat faeces for use as fertiliser.

The caves are also known for their edible birds' nests, made out of the glutinous saliva of millions of swiftlets. The nests are collected by labourers who risk their lives to reach the ceiling of the caves at a height of some 50 metres or higher.

The park is one of the most popular tourist attractions in Sarawak and attracts 15,000 visitors every year.