As with much of Borneo, the rivers at Mulu form the primary means of motorised transport. The steep topography and high rainfall of the park make for fairly turbulent rivers and most of the river access is restricted to the rivers flowing on the park’s boundaries in the lowland areas. Even by equatorial standards, Mulu has a high annual rainfall with an average of five to six metres and some areas having recorded an annual rainfall well in excess of six metres. Fortunately weather patterns in the park are reasonably consistent with mostly clear mornings and early afternoons and showers in the late afternoon or evening.


Trekking in the park allows visitors to truly appreciate the spectacular nature and beauty of the riverine areas. Most well known is the Melinau Gorge, which is formed between Gunung Api and Gunung Benarat in the upper reaches of the Melinau River. The gorge forms the backdrop to Camp 5 and includes spectacular views of Tiger Cave located high on the southern cliff face of Benarat. In addition to the Melinau there are several other spectacular river courses and gorges, including the Melinau Paku River along the Summit Trail, the waterways flowing into and out of the caves in the Garden of Eden and the Langsat River, which flows from the park into the Tutoh River on its southern boundary.