Maliau Basin, Protected rainforest area in Sabah, Malaysia.

Maliau Basin is a protected rainforest area in Sabah featuring a distinctive circular formation created by steep surrounding cliffs. Its interior contains approximately 390 square kilometers of undisturbed forest with multiple ecological layers and several cascading waterfalls.

The area was first recorded in 1947 when a pilot spotted its distinctive circular shape during a flight over Sabah. Since then it has become a focus for scientific research into pristine forest ecosystems.

The name Maliau comes from the Maliau River, the single stream that drains the basin, flowing out through a gap in its southeastern rim to join the Kuamut and then the Kinabatangan. The basin has never been permanently settled, so there is no village life or farming tradition inside it; the forest is used for research and education instead.

Visitors must obtain a permit and register at the Maliau Basin Studies Centre located about 27 kilometers from the main entrance gate. It is worth planning ahead since access is controlled and conditions can vary depending on weather and seasonal changes.

The basin is drained by a single river: the Maliau leaves through a gap in the southeastern rim, joins the Kuamut and reaches the Kinabatangan, Malaysia's second-longest river after the Rajang. The near-circular rim, visible from the air, encloses 390 sq km of forest that has never been permanently settled.