The Kinabatangan River () is a river in Sandakan Division, in northeastern Sabah, Malaysia. It is the second longest river in Malaysia, with a length of from its headwaters in the mountains of southwest Sabah, to its outlet at the Sulu Sea, east of Sandakan. The area is known for its high-biodiversity habitats, including its limestone caves at Gomantong hill, dryland dipterocarp forests, riverine forest, freshwater swamp forest, oxbow lakes and salty mangrove swamps near the coast. Etymology and history With the early Chinese traders' settlement around the river mouth area, the name Kina Batañgan was used by the indigenous people of the area for the river, with the word Kina being a reference by the indigenous Dusun for the Chinese people. The Orang Sungai traditionally lived along the river banks and were of mixed ancestry, including Dusun, Suluk, Bugis, Bajau as well the Chinese. The earliest Chinese traders settlement on the banks of the Kinabatangan River had been established since the 7th century, where they traded in edible-nest swiftlet, beeswax, rattan and ivory. In the 15th century, a sister of the Chinese Kinabatangan settlement leader married the sultan of Brunei. During the British North Borneo era, the river served as the route for goods and timber exports, navigable for steam launches as well for smaller boats. William Burgess Pryer attempted to establish a market at one location called Domingol along the river coast, but the plan did not flourish. Geology and ecology The river area, including Labang and Kuamut, were formed by the Early and Middle Miocene periods, while large parts of the river system from the Maliau Basin were formed during the Early and Late Miocene. Towards the river mouth, the area is made of Middle Miocene chaotic deposits. The ecology of the upper reaches of the river has been severely disrupted by excessive logging and clearing of land for plantations, although the original lowland forest and mangrove swamps near the coast have largely survived, providing sanctuary for a population of saltwater crocodiles (Crocodylus porosus) and containing some of Borneo's highest concentrations of wildlife. In many villages along the river, the demand for freshwater fish has always been high, and the livelihoods of villagers have greatly depended on the income from catches. Each year, the lashing rains of the northeast monsoon cause the river to swell rapidly. Unable to disgorge into the sea quickly enough, the river frequently