“There’s one thing you learn in the jungle,” says nature guide Allen Patrick, as he leads the way along a trail edged by ferns and soaring trees. “It’s never quiet.” He cocks a ear to listen to the cacophony of sounds: screeching birds, humming crickets and whooping gibbons, underpinned by the constant chainsaw buzz of insects.
A hooting call rings out, descending into a throaty cackle that sounds eerily close to a human laugh. It’s a helmeted hornbill, Allen explains, one of eight hornbill species found in the Maliau Basin. “Some people call them the joker of the jungle. It’s a good name.” Located 48km north of the Indonesian border, the Maliau Basin is known as Sabah’s ‘lost world’ for a reason. A vast river basin encircled by a nearly impenetrable ring of rock, it contains some of the largest remaining tracts of virgin jungle in Borneo. The basin was discovered by chance in 1947, when a British pilot almost crashed into its rim, but the first organised scientific expedition to the area wasn’t until 1988.

The scientists were amazed by what they found. This expanse of jungle harbours an estimated 2,40,000 species – two-fifths of all the animals, plants and insects found in Borneo. It’s one of the world’s great cradles of biodiversity, and is home to some of its rarest species: Malayan sun bears, pygmy elephants, clouded leopards and the Sumatran rhino. Giant flying squirrels and red leaf monkeys caper through the trees; rare lichens and rafflesia flowers bloom on the forest floor; hidden rivers and waterfalls flow through the jungle, past agathis and seraya trees as tall as seven-storey buildings.
Even today, only around half of the basin has been explored; fewer than 2,000 people are thought to have set foot inside the basin’s rim. And, on an island where the rainforest is disappearing at an alarming rate, Maliau has become a potent symbol of the need for Borneo to preserve its natural heritage while there’s time. “It’s important that we look after Maliau,” Allen muses, as he leads the way across a bridge suspended high in the jungle canopy. Dappled light rains down and colourful birds flit through the tree tops. “I don’t know anywhere else quite like this.” Part of the reason for Maliau’s survival is its isolation. From the rim, it’s a two-hour drive to the nearest asphalt road.
The interior of the basin can only be reached via a day’s hard trekking and its handful of camps is equipped with minimal facilities. Maliau’s wildness is exactly what makes it precious; a stay on the rim more than acquaints you with this unique appeal. “There’s not much room left for wild places,” says Allen, as darkness descends on the jungle and bats flutter home to roost. “But, once they are gone, we have no way of getting them back. And, without them, Borneo will be a much poorer place.”