Lake Linumunsut
A freshwater lake inside the Maliau Basin Conservation Area that is geologically unusual for Sabah, and almost never visited. It is not on any standard itinerary, which is worth knowing before you build a trip around it.
What makes Lake Linumunsut unusual
Most freshwater lakes in Sabah are oxbows — former river meanders cut off from the main channel as it shifted course, leaving a crescent of standing water. They are common along the Kinabatangan and they are a normal feature of any large lowland river system.
Lake Linumunsut is thought to be the only freshwater lake in Sabah that is not an oxbow. That makes it a genuine geological curiosity rather than a scenic footnote, and it is one of the reasons the conservation area boundary was extended to take it in.
Where it sits
Not inside the basin proper. The Maliau Basin Conservation Area covers 588.4 square kilometres, of which the basin itself accounts for about 390. The remaining 198.4 square kilometres is forested land east and north of the escarpment rim, added when the boundary was extended, and Lake Linumunsut lies within that extension.
So it is inside the conservation area but outside the saucer. More on the basin's geography here.
img/linumunsut-lake.jpgLake Linumunsut in the conservation area extension21/9Fossil evidence in the surrounding rock
The wider area holds something more surprising than a lake. Fossilised marine gastropods have been recorded in the surrounding sedimentary rock, dated to roughly 16 to 17 million years old.
Sea snails, several hundred kilometres inland, at altitude, in the middle of Borneo. It is direct physical evidence that the sandstone and mudstone beds forming the basin were laid down in a marine environment before being uplifted. The basin looks like a crater and is often described as one, but it is a sedimentary formation, and this is the sort of evidence that settles the question. The stepped landscape those tilted beds produce is also why Maliau has more waterfalls than anywhere else in Malaysia.
Can you visit Lake Linumunsut?
Not on a standard package. None of the four commonly sold itineraries goes there — the two Studies Centre packages stay near the centre, and the two trekking loops run through the interior in the opposite direction.
This is a specific instance of a general truth about Maliau. Roughly a third of the conservation area is open to visitors at all, and less than half has been properly explored even by researchers. A great deal of what you can read about exists outside anything you can book.
If Lake Linumunsut is genuinely the reason you want to come, raise it at the enquiry stage and expect a custom itinerary, considerable lead time, and a real possibility that the answer is no. Access to parts of the conservation area is restricted regardless of budget, and permission comes from Yayasan Sabah rather than from an operator. How permits work.
Lake Linumunsut questions
What is Lake Linumunsut?
A freshwater lake within the Maliau Basin Conservation Area, thought to be the only lake in Sabah that is not an oxbow. It lies in the extension area east and north of the escarpment rim rather than inside the basin proper.
Can you visit Lake Linumunsut?
Not on any of the four standard Maliau Basin packages. The Studies Centre itineraries stay near the centre and the trekking loops run through the interior in the opposite direction. It would require a custom itinerary and separate permission from Yayasan Sabah.
Why is Lake Linumunsut geologically significant?
Most freshwater lakes in Sabah are oxbows, formed when river meanders are cut off from the main channel. Lake Linumunsut is thought to be the only one that is not, making it a genuine geological outlier.
Are there fossils at Maliau Basin?
Yes. Fossilised marine gastropods roughly 16 to 17 million years old have been recorded in the sedimentary rock of the area, evidence that the sandstone and mudstone beds forming the basin were laid down in a marine environment before uplift.
Is Lake Linumunsut inside the Maliau Basin?
Inside the conservation area but outside the basin itself. The conservation area covers 588.4 square kilometres, of which the basin accounts for about 390. The lake sits in the 198.4 square kilometre extension area beyond the rim.
Interested in the extension area?
Anything outside the standard circuit needs a custom itinerary and long lead times. Tell us what you have in mind.
Enquire How permits work