The 4 Impressive Caves of Mulu National Park

The Mulu National Park is a wonderland for any nature lover.

They have imposing caves, dense tropical forests, challenging mountains, and strange animals and plants. It is no wonder that the National Park was inscribed as a UNESCO World Heritage site in 2000. What made the status even more mind-boggling is that the park meets not one but all four criteria!

Apart from the show caves, Mulu National Park is also home to the RM 100 visage of the Pinnacles. Mulu aside, if you’re a cave fanatic, know that Miri, the nearest town to Mulu, has an impressive and less-known cave to boot! And while we’re at the attraction of Miri, why not check out this post of mine on the places I visited across Miri and Mulu?

For now, let’s dive into this post dedicated to the impressive show caves of Mulu National Park.

This trip happened in Jul 2022. This post contains affiliate links that cost nothing to you but support my blog! It may also be updated periodically. Cheers!

Day 1/ Late Afternoon: Deer & Lang Caves

The Deer Cave is the representative cave anyone would have known even before visiting the cave or the park – have a look at all the tour brochures (if you managed to get one).

The entrances into both camps are about 3 km on the boardwalk from Mulu HQ. We saw lots of interesting critters, including a pair of mating millipedes, several quirky plants and a resting Bornean Keeled Pit Viper!

While Deer and Lang Caves look vastly different, their passages connect. Several sources claim the entrance of the Deer Cave is the largest in the world, though many differ and point to Hang Son Doong in Vietnam or the Mammoth Cave in the USA as the biggest. I am no cave expert but be my guest to look around and tell me what you have found!

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Deer Cave

The cave was the largest in the world until the discovery of Son Doong Cave in Vietnam. But before the rediscovery of Hang Son Doong in 2009-10, the Deer Cave was the biggest with chambers ranging from 120 – 150 m in width and a staggering height of 197 m. Hang Son Doong has a width of 160 m and a height of 200 m.

Unlike Hang Son Doong, which does not have a noticeable bat population, an estimated 2-3 million wrinkle-lipped bats across more than 12 species reside in the Deer Cave. These nocturnal creatures comb through the forest every night and consume about 15 tons of insects, keeping pests like mozzies under control.

Remember to check out the often neglected educational boards behind the Bats Observatory if you can! I gleaned those bats' info from the boards. Someone has meticulously simplified the information on bats of Mulu for us laymen in a humorous way.

Why is the Deer Cave called the Deer Cave?

Herbivorous animals, like the ubiquitous deer (back then), need salt to supplement their diet. Guano – a mixture of liquid and solid excrement from the birds and bats – contains salt. The salt leaches out to form concentrated deposits known as salt licks which supplement the deer’s needs. Any good hunter would wait for the deers in the cave for an easy hunt, and that was how the name stuck.

As with all the show caves in Mulu National Park, there’s a long boardwalk fitted with dim lights within the cave. That said, having your own light source like a headlamp still comes in handy for certain darker areas. We covered over 500 m of these boardwalks in the Deer Cave.

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Lang Cave

The distance between the entrance of Deer Cave and Lang Cave is a mere 5 mins walk.

Unlike Deer Cave, which is damp with grounds peppered with guano, and a high ceiling with millions of bats and birds, Lang cave is wet, has low-hanging stalactites and stalagmites, and is very quiet.

Lang Cave was discovered in 1977 by a local Berawan man named Lang Belarek. The cave took the name of its discoverer.

Some of the impressive sights we encountered include a jellyfish-like stalagmite, rock pillars from conjoined stalactites and stalagmites, and straw-like stalactites protruding from the cave ceiling.

While the strange rock formations are within our reach and you may be tempted to touch one, please refrain! The oil and dirt from our fingers could blacken and destroy the rock formations that have taken aeons to form!

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Bat Exodus

We left the caves for the daily Bats Observatory from 5 – 6.30 pm (the show gets cancelled if it rains 😜). Batches of bats exited the caves in swirling clouds like swarms of bees. Some looked like breathing black balls, some came out in a long wriggling mass, and some stuck close to the mountain edge before dispersing out.

As night fell, we brisk-walked back to Mulu HQ for dinner, nature’s cacophony keeping us company.

Read more about both caves from this Nat-Geo article, and figure why a team still thinks it is a strong contender for the title of the largest cave passage in the world.

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Day 2/ Early Morning: Wind & Clearwater Caves

These two caves reside in the heart of the national park. Unlike the Deer and Lang Caves, we had to catch a longboat and cruise up the Melinau River to reach the caves.

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Wind Cave

There are two entrances into the Wind Cave: one that is forever half-submerged by the Melinau River and another located on higher grounds reachable via a long ramp and steps.

The cave caught its name from the cool breezes blowing through it, which became apparent at a particularly narrow passage of the 350 m-long route.

Scalloped walls, another unique rock formation carved out from the river, was the first unique formation we saw at the entrance. We could hear this same river that carved the walls working its way further down into the cave, widening old passageways and creating new ones.

Apart from the scalloped walls and whistling wind, what sets the Wind Cave apart is its biggest chamber – the King’s Chamber. An impressive array of stalagmites, stalactites and the fusion of both grew like trees in this limestone wonderland.

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Clearwater Cave

We had tea by a pool after Wind Cave. And that was how our last cave caught its name – from the crystal clear waters. Reaching the entrance of Clearwater Cave took effort, and we sweated away the calories we had for tea over the 200+ odd steps.

The Clearwater Cave is the longest cave system in Southeast Asia and the 9th longest in the world at over 200 km. An underground river bubbles within the cave. You could actually sign up for adventurous caving and waddle into its chambers.

This impressive cave system was first discovered in 1978. Since then, numerous studies have taken place, resulting in the discovery of more chambers and longer passageways. It’s no surprise then, that the adjacent Wind Cave is connected to Clearwater Cave too. Who knows what future expeditions would find!

While its extensive length is impressive, non-cave professionals like us will never fully grasp its magnitude. What made this cave unique to me is its underground river, a doline filled with endemic one-leaf plants, and an abundance of phytokarst.

Having seen a dizzying amount of stalagmites and stalactites, phytokarst was new to the list. These strange spiky rock formations came from the biological degradation of the limestone. Bacteria and algae growing on the rocks produce waste that eats into the rock surfaces. As these living organisms favour the sun, phytokarsts are found in areas with sun exposure, their jagged spikes pointing towards the light.

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More Pointers

Tour Package or Independent

We went with a tour package as we had no time to plan and needed this trip to happen. If time is by your side, you potentially could shave off some costs by booking directly with the National Park. Going with a tour package, however, does have its perks as we were always the first to arrive at any site and did not have to worry about food or accommodation.

Mulu National Park Pass

All visitors have to purchase a 5-day pass to enter the park. The pass is usually a plastic band tied around the wrist. I had a pink one but spotted some wearing blue bands on other days.

It costs RM30 for foreigners and RM15 for Malaysians.

Most of the treks in the park, including the show caves, are guided and require additional fees.

Planning

Tour packages usually put the visit to the Deer and Lang Caves on the first day of the itinerary when visitors arrive before 3 pm as the guided tour starts at 4 pm.

If you arrive after 3 pm, you could do free walks in the park and arrange to visit the Wind and Clearwater Caves in the morning – they start at 8 am and end before 2 pm – and end the day with the Deer and Lang Caves.

We spent the following morning visiting the Wind and Clearwater Caves and that afternoon hiking into Camp 5 for the Pinnacles Track.

Getting There

There is only one way to reach Mulu National park – by air. Maswings have direct flights from Miri (30 mins), Kuching (1h 20 mins) and Kota Kinabalu (55 mins) every day.

We took the 30 mins flight from Miri to Mulu, which felt more like a fun ride. Ten minutes up in the air, and tea – consisting of a cake and a drink – was served. We had barely started eating before the pilot announced we would be landing shortly. It costs us RM 280 (less than SGD 100) for a return flight.

Accommodation

We stayed in the National Park except on the nights when we were in for the Pinnacles. There are several options to go with – from hostel beds to bungalows. As the prices are reasonable for the facilities and convenience, these places tend to be very popular. Book in advance to avoid disappointment. The National Park has a cafe. Prices tend to err on the expensive side since food is mostly flown in. 

Marriott Mulu

If you are looking for a 5-star hotel, there is a Marriott right around the corner from the National Park.

Homestay/ Hostel

A handful of basic homestays and backpackers are located outside the National Park. Check out AA Homestay and the Mulu Village. Both have excellent reviews.

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Difficulty

Visiting the caves is not difficult. We saw parents with children in tow visiting the show caves. Dress sensibly. You could wear slippers like our guide if you know where to place your foot as some areas are slippery. We wore a mix of hiking boots and walking sandals.

And that is all from me about the four gorgeous show caves of Mulu National Park. Be sure to add this to your itinerary should you be visiting Borneo. Mulu National Park does not disappoint!