After our wild adventure in Indonesian Borneo, we were not quite sure what to expect from the Malaysian side of the island. In Indonesian Borneo, tourists were rare enough that we had our photos taken by gas station attendants and passersby. In contrast, Sabah and Sarawak – the two Malaysian States in Borneo – are swarming with tourists from all over the world. For the last month we have been traveling through the famous national parks here, from Kinabalu in Sabah to Gunung Mulu, Kubah, and Bako in Sarawak.

After leaving Kinabalu, we flew to the city of Miri in Sarawak and then on to the small town of Mulu. The travel day was noteworthy. First, we discovered stores in the airport of Kota Kinabalu that sold dried and frozen fish. These were located both in and out of security and you could have your purchase wrapped up as carryon luggage. It was the first time my laptop has gone through the security scanner between a block of frozen prawns and a whole fish. The flight also got progressively smellier as the items began to thaw.

Getting to Gunung Mulu National Park was relatively easy, but it was certainly out of the way. The airport consists of a tiny runway and one gate and the national park is the only destination there. As we landed, flying over the giant mountains and limestone hills of Mulu, we were sure it was worth the effort.

Gunung Mulu is a World Heritage Site and is most famous for its extensive cave formations and for a colony of two to three million bats that lives within Deer Cave, the cave with second largest cave passage in the world. It is easy to sign up for tours of the caves at the well-run park headquarters, where you can opt between a simple hike or a caving adventure.

On our first night in the park, we decided to hike down to the bat viewing platform – an open amphitheater that has been built outside of the caves so that tourists can observe the bats coming out to hunt. We arrived a bit too late, having been caught up with insects and birds we found along the way. We did however hear the bats as they flew overhead. What sounded like large gusts of wind turned out to be the wing beats of thousands upon thousands of bats on their way to hunt.

On a good night, it is possible to see hundreds of thousands of bats coming out of the caves in a stream. This incredible sight is referred to as the “bat exodus.” Due to weather, we did not witness the full spectacle until our final evening in the park, a night that made all other viewings pale in comparison. As bats streamed out in a never-ending ribbon, I could only laugh in amazement.

On our other days at Mulu, we hiked the forest trails and went on a few of the cave tours. Some sightings of note included a group of crested fireback pheasants and some spiky forest lizards. From the canopy walkway – the longest tree-based walkway in the world – we saw shiny sunbirds and resplendent barbets.

The caves made me feel like we had gone back in time. Their enormous mouths were coated in lush vegetation and tree ferns grew in small groves in the shade of their precipices. It would not have surprised me in the slightest if a pterodactyl had flown over or if a a stegosaurus lumbered out of the cave. Inside the caves, we saw impressive formations resembling jellyfish, eagles, and even the profile of Abraham Lincoln. In Clearwater Cave, I stood transfixed as we watched an underground river coursing along the cave’s rocky bottom.

What delighted me about Mulu was also the campy atmosphere. Tourists were friendly with one another and many of the people we met were highly interested in natural history. One man had come just to see the endemic plants in the higher reaches of the park. Another man, a biology professor from Oregon, was interested in the whole spectrum of Mulu’s natural wonders. I enjoyed sharing our findings with other enthusiasts and hearing about their sightings. One day, we even came across a Russian couple who had just discovered two gliding geckos engaged in a death struggle. We all kneeled on the ground, observing the two creatures as they stayed locked together – one biting an arm and the other biting an eye.

Gunung Mulu turned out to be a highlight of our travels in Borneo. Between the caves, the bats, and the other wildlife, we hardly stopped moving for five days. Our next stop . . . Kubah National Park in Sarawak.