A Borneo Jungle Adventure – Mountains, Caves and Bats

If you’ve been wanting to have a real jungle adventure there’s no better place to find one than in Borneo. Gunung Mulu National Park is set in the middle of a dense jungle in the Malaysian state of Sarawak. It has thick forests, steep mountains, bat filled caves and meandering rivers all waiting to be explored.

Jungle Walks

Gunung Mulu National Park is a great tourist site with boardwalk trails, canopy walks, hiking trails and river trips allowing you to see the jungle from many perspectives. Over 5 days we saw many of this jungle’s interesting flora, creepy bugs, endemic butterflies and bees.

An interesting tree in the Borneo jungle is the Tajem tree. Its sap is poisonous and was once used by the indigenous Penan people. They put the sap on the tips of their blow darts, poisoning their targets. We saw a few of these large trees that had old cuts in the bark, presumably by ancient tribesmen.

The Caves

Gunung Mulu National Park was designated as a UNESCO World Heritage Area because of its many large caves. Even though Lang Cave is one of the smallest caves in this park, it is still very large. Inside, huge chambers house thousands of stalactites and stalagmites. Water drips down from the limestone ceiling continuously building these features until the stalactites and stalagmites join to form columns. In the process, these features develop interesting shapes with intricate features. The stalactites, stalagmites and columns inside Lang Cave made it the most beautiful of all of the caves in the park.

Beside Lang Cave is Deer Cave. It is one of the largest caves in the world and has a resident population of over 3 million wrinkled bats. This large number of bats have made huge mounds of bat guano inside the cave. As you approach the cave you can smell the guano, even before you can see the entrance. Inside, the smell is suffocating. At the far end of the cave is a lush garden where the roof collapsed and the jungle has taken over.

One of the biggest thrills is to be at the cave at dusk to see 3 million bats exit the cave en masse to feed on bugs. We weren’t the only ones watching these bats, however. Bat Hawks soar above the cave’s entrance anticipating the event. At dusk, groups of thousands of bats stream out of the cave. In unison they twist and turn like a tornado as they try to escape their enemy bat hawks.

If it rains, the bats don’t exit. On our first night, we heard a strange honking sound from the jungle. Our guide told us that it was the Malayan Horn Frog. Their calls indicate that rain is coming. Sure enough, 10 minutes later it began to rain and the bats didn’t exit the cave. On our third night, we finally saw the show as millions of bats swirled out of the cave. Bat Hawks swooped in and out of the swirl, trying to catch their own meal. It was an awesome display of wildlife survival.

Two other Mulu caves are Wind and Clearwater Caves. At the entrance to Wind Cave the interesting rock formations are covered in single-leaf plants. The Melinau River flows through the Clearwater cave. Rushing water over thousands of years have slowly eroded the cave walls leaving behind beautiful etchings.

The Pinnacles HikE

Our next adventure was a trek to see the famous karst formation pinnacles on Gunung Api (Mount Api). The start of the hike is in a very remote location. We took a 45 minute boat ride up the Melinau River on a wooden long-boat and then an 8 km trek along the river. The hike started easy but not long after we started walking it began to rain. It poured heavily for an hour. The rain was so intense that we were soaked after the first 2 minutes. The bigger problem was that the rain brought out leeches. By the time we arrived at camp, Richard had pulled off 8 blood filled leeches and Maggie had 6! Not a great start to this adventure.

Due to the remoteness and difficulty accessing the area most people spend two nights at Camp 4. There is a long-house with a dining room, kitchen and a few dorm style rooms. Each bed has mosquito netting. The mosquitos actually weren’t bad, but the bees were horrible. There seemed to be thousands of bees swarming around camp. One man in our group wasn’t careful when tucking in his mosquito netting allowing dozens of bees to get inside. The bees found their way in, but couldn’t get out. Eventually, he found a way to safely coax them out of his bed.

You are required to have a guide for the hike to the pinnacles. We hired a park ranger as our guide instead of going with a large tour group. At 6:30 the next morning we started the 2.4 km, 1,600 m elevation scramble. We climb and hike a lot, so didn’t think it would be too difficult, but we don’t usually climb in a rain forest. The trail is very steep. The 45⁰ – 60⁰ incline had us crawling over slippery, mossy roots, mud and sharp limestone. In places it was so rough we had to grab on to fixed ropes. Near the top, it was even more difficult. Eighteen ladders were the only way to get up the cliffs.

As the trail approached the summit, we saw several carnivorous pitcher plants. These interesting looking plants come in many sizes and colours and all have a deep basin to collect water and trap bugs.

Finally, almost 3 hours later, we reached the incredible viewpoint. In front of us were dramatic, razor sharp, karst limestone pinnacles. They were formed by hundreds of years of rain water wearing down the exposed limestone into these beautiful formations. It is a stunning scene and worth the tough climb.

Getting to the summit was only half of the battle as we now had to retrace our steps down that steep, slippery trail.  After another 2 1/2 hours, we were back at our camp and welcomed a refreshing dip in the Melinau river. This is the same river than ran through Clearwater Cave. As we relaxed at camp we were joined by dozens of beautiful butterflies, including the endemic Rajah Brooke’s Birdwing. It’s a gorgeous butterfly with bright blue-green wings. They are quite large with a wingspan of 16-17 cm.

The next day we hiked the 8 km back to the boat dock. It rained overnight but not during our hike and yet Maggie had another 4 leeches and Richard had another 6!

Our Penan Village Experience

We had the opportunity to spend 2 days with a local Penan guide in the village of Long Iman. Penans are historically nomadic, indigenous people of Borneo. Their ancestors were headhunters but they stopped practicing this in late 1890. Many Penans have made permanent settlements by living in longhouses, but some still live as nomads. We stayed in one of these remote village, where we saw traditional ways of life of the Penan people.

Over the two days our guide took us hiking into the jungle. One day we visited a gorgeous private waterfall. It was so nice to swim in the clear water with no one else around. The second day we hiked to a secret cave that had been used by the Penan people centuries ago. He showed us broken pottery and human bones that were left by ancient tribes. We were only the second group of non-Penans to visit the cave. It was quite exciting.

We wrote more about this fascinating trip in Our Penan Village Adventure. The post includes information on how you could also visit this village.

Getting to Gunnung Mulu National Park – This remote park is only accessible only by plane. Maswings Airline flies into the town of Mulu from a few different cities in Borneo.

Where to eat and stay – There is a wide range of accommodation for most budgets. Outside of the park are very basic guest houses and a luxury resort. Inside the park are government-run long-houses and cabins. Before booking, check to ensure they have a generator that will run throughout the day and night. Our guesthouse’s generator didn’t run all night so the fan stopped working and our room was very hot.

There are a few basic restaurants near the park gates and a cafeteria inside the park.


Coming up next – Myanmar – The Ancient City of Mrauk-U

For more pics from our blogs go to Gallery at monkeystale.ca

To read more of our adventures go to Destinations.

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