Ulu Temburong National Park is the first national park of Brunei, 50,000 hectares of primary Borneo rainforest in the Temburong district, reached by longboat up a shallow river and climbed into on a walkway fifty metres above the ground, and almost all of it is closed, with visitors kept to one corner so that the rest stays as it has always been. Temburong is cut off from the rest of Brunei by a strip of Malaysian land taken by the rajahs of Sarawak in 1890, so the park sits in an exclave of its own country, reached by a bridge opened in 2020 or by speedboat through the mangroves from the capital; the last hour in is made in a narrow wooden Iban longboat, whose boatmen read the rapids and gravel bars by eye and thread between them at speed, past forest that has never been cut, to the park headquarters at the meeting of two rivers. The canopy walkway is reached by aluminium ladders caged in wire mesh, bolted stage by stage into a ridge and climbed one person at a time, until the trunks that were overhead are beneath the feet and the forest runs unbroken, ridge after ridge, to the horizon.
The forest is the point, and it has been measured. The field centre inside the park found that a single rainforest tree here can carry roughly four hundred species of beetle, most of them living metres above anyone's head, and hornbills, gibbons and flying lizards are seen from the walkway in the early morning. In the forest below the towers clear water slides over slabs of black rock into pools cold enough to be a shock in the humidity, with fish that nibble the feet, and the visit ends with a swim before the longboat back. February and March bring the least rain and the clearest air, and the northeast monsoon can raise the river a couple of metres in hours and postpone the boats. Ulu Temburong is a forest a country decided not to touch, and the walkway is the one window into it.