I Flew 9 Hrs to Watch The Bat Exodus in Borneo – What I Experienced Was Pure Magic!

Every time my spouse exclaims “Surprise me!” just like Anton from Ratatouille, I roll my sleeves and get to hysterically looking for off-the-grid things to immerse in. Always something closer to nature, it isn’t for ‘gram or ticking a checkbox, it is the insatiable desire to learn more about what’s around us. This led me to the bat exodus in Borneo where you get to watch and feel three million of these flying mammals in action!

Visiting national parks wherever we go is a norm and experiencing something extraordinary is what led me to their official website. Popularly known for the Pinnacle Trek that’s undertaken over three days, Mulu offers a lot more than just its stunning Pinnacles. Although an amazing experience to savour, I knew I wasn’t cut out for that trek because of the last leg that required climbing past sharp edges of the pinnacles to reach the top. Instead, I focused on other activities within the park – that’s when I found about the Bat Exodus by more than three million bats, occurring every single day!

Surreality!

The day started with self-touring. The boardwalk before me stretched like a spine of weathered timber, 3.8 kilometers of raised planks that snaked through the peat swamp and limestone outcrops of Borneo’s ancient rainforest. There I was walking with a group of strangers to ring in a shared experience of nature’s divinity.

Before heading to the amphitheater, we stopped by the show caves – Lang and then Deer. Deer Cave was yawning before me like a wound in the limestone hill, except it’s not a wound at all, but an opening at 122 meters high and 174 meters wide -among the largest limestone cave passages on earth! Sunlight poured through that gaping mouth, illuminating a chamber so vast that the distant wall fades into shadow.

The Penan people once hunted deer here, hence the name. But the deer are long gone, frightened away by decades of visitors. What remains is something far more numerous. The smell hit me first, subtly as I stepped inside the belly – sharp, acrid punch of ammonia that signals you’re standing beneath one of the world’s largest bat colonies. Twelve species call this cave home, with the wrinkle-lipped bat making up the bulk of the population – nearly 3.5 million in all!

The viewing area starts filling by 4 pm and we were running late. By the time we reached around 5:20 pm, it as full – everyone occupying the most strategic spots.

The guides had warned us, silence is not just courtesy – it’s strategy. Noise sends the bats flying higher, but silence allows them to fly lower, close enough that we might hear the sound of their wings! We wait in hushed stillness, watching that dark maw in the limestone.

Nothing happened. Everyone was growing impatient.

The sun begins its inevitable slide toward the horizon, painting the sky in shades of amber and rose. Still nothing. I check my watch. Then the sky again. Then the cave mouth. Although a patient person when it came to wildlife spotting, patience was running thin as we were losing sunlight.

Then my spouse pointed at a circling donut in the sky! The first plume had emerged.

It began as a wisp, a tendril of smoke against the darkening cave mouth. But smoke doesn’t move like this. Smoke doesn’t spiral and coil with such purpose.

The bats circled inside the chamber first, forming a close-knit round before spilling out into the open air. A survival strategy, I learned later, to confuse the eagles that patrol this hour like fighter jets awaiting takeoff clearance. By swirling together and moving as one undulating mass, the bats make it nearly impossible for predators to single out an individual.

Within minutes, the wisp becomes a torrent. The bats pour out in an unbroken stream, a black river flowing into the sky. They twist into columns, then unfurl into ribbons, then gather again into shapes that defy description. It’s murmuration, but on a scale that dwarfs anything I’ve witnessed from birds. Nearly 3.5 million bodies, each no larger than my thumb, moving with the synchronicity of a single organism!

I forget to breathe.

The stream lasts not minutes but nearly an hour, an endless exhalation of life from the cave’s depths. At its peak, the bats fly at speeds up to 70 kilometers per hour, traveling as far as 50 kilometers into the night to hunt. Six tons of insects will disappear into those millions of stomachs before dawn.

Then comes the sound.

For the first hour, we’ve heard nothing but the whisper of wind and the distant call of birds. But as the light fades and the bats fly lower, a new layer emerges: the sound of wings. Not the leathery flap I’d imagined, but something softer “like the gentle patter of applause,” as one guide poetically described it. A million tiny hands clapping in the dusk.

The return journey along the plank walk feels different. The jungle, quiet during our outward trek, has woken to its nocturnal symphony. Cicadas chirp, frogs honk, and somewhere in the darkness, something large rustles through the undergrowth. We walk faster than we came, our flashlights cutting narrow tunnels through the absolute black.

Above us, the canopy rustles. The first gusts of an approaching storm warn of rain to come. We hurry, not because we fear the weather – this is Borneo, after all, and rain is as certain as sunrise – but because we’re eager to reach our longboats, our bungalows, our notebooks.

Behind us, three million bats are hunting. Tomorrow evening, they’ll do it again. And the evening after that, and the evening after that, for as long as this ancient cave stands and this ancient forest breathes.

I’ve traveled enough to know that some things resist documentation. I took photos – we all did – but they’re inadequate. Black smudges against a darkening sky. Motion blur where there should be precision. Nothing captures the sound of a million wings applauding the night.

The guides at Mulu will tell you that the bat exodus happens every evening, weather permitting. They’ll give you the statistics: three million bats, twelve species, 70 kilometers per hour. They’ll warn you to be silent and patient.

What they won’t tell you – what they can’t tell you – is how it feels to stand beneath that living river, to watch the sky turn to smoke, to hear evolution’s greatest survival strategy playing out in real time. That, I suppose, is why we travel. That’s why we endure the flights and the boat rides and the three-kilometer boardwalk treks.

Because some things cannot be described. They can only be witnessed.

And I was witness.

A thoughtfully carved into the hillside amphitheater where you can literally lie on your backs as you watch the cinematic ribbon-like patterns created on the vast blue sky by the bats.

The first leg of the journey should lands you at Kuala Lumpur International Airport from your home country.

Then next leg consists of either flying from Kuala Lumpur to Kuching (south of Sarawak) or Miri (north of Sarawak) which is closer to Mulu. I would suggest booking the flight to Miri.

The third leg includes flying from Lulu Airport to Mulu Airport whose runway is right in the middle of the wilderness of Mulu National Park. The flight is hardly 15 mins long!

If you are looking for budget stay, there are eight local homestays one can book. Some include breakfast too. In case you want to stay somewhere premium then you can either book one of the cottages within Mulu National Park or a luxurious stay Mulu Marriott which runs shuttle very few minutes to Mulu National Park.

This is a free activity! There is no booking to be made. If there is anyone selling tickets for this activity then sprint away!. You only have to pay for Gunung Mulu Park Entrance fees that’s valid for 5 days! This pass can only be booked at the Mulu National Park Ticket Counter.

* Conversion Rates are subjected to change

A tropical forest that receives 4000-6000 mm of rain annually and over 260 days a year, checking for the best time to visit Mulu National Park may never appear right enough!

To witness the Bat Exodus, you need a clear sky and no rain. A slight imperceptible drizzle doesn’t dampen the bats’ spirit but if the drizzle turns into a torrent, then it’s a no-go for them.

Borneo is unpredictable. One moment rain, the next moment sunshine. Which is why you must wait at the amphitheater for the magic to unfold. It’s a gamble worth the bet!    

Slather yourself with insect repellant but NOT ODOMOS. Use their local one.

Wear long sleeves to avoid heat and tan.

The walk is a long one through a national park. Carry water to avoid dehydration.

A tropical forest receiving as much rainfall, sudden showers are natural. Carry raincoat, rain-poncho or umbrella (although this might hardly help)

The mass evening emergence of cave-dwelling bats as they depart to hunt – nature’s original rush hour, involving millions of bodies moving as one living river against the darkening sky. Spiraling upward along the cliff face like smoke from an invisible fire before unfurling across the rainforest in twisting ribbons, they are estimated to consume between five to ten grams of insects each night.

Weather permitting, the bats stage their grand exit most evenings between 5:30 and 6:30—though occasionally they’re either fashionably late or simply can’t be bothered to leave at all. On rare overachieving days, they’ve been spotted heading out as early as 4:30 PM, embarking on round trips that can stretch up to 100 kilometers from home before slipping back in by dawn. Once airborne, they cruise at a breezy 75 kilometers per hour, casually commuting at altitudes of 3,500 meters – which, for context, is roughly the height at which small aircraft start getting nervous.

At the heart of the park looms Gunung Mulu, a 2,377-meter sandstone giant that spends most of its time wearing a crown of clouds. Beneath it lies one of the earth’s most impressive secrets: over 295 kilometers of explored caves and counting –carved into existence drop by patient drop. These caverns serve as high-rise housing for millions of swiftlets and bats, who clearly appreciate good real estate. The crown jewel? Sarawak Chamber. At 600 meters long, 415 meters wide, and 80 meters high, it’s so absurdly spacious that you could park entire city blocks inside—and still have room for a football match. St Peter’s Basilica? Cute. This chamber could swallow it whole and ask for seconds.

Deer Cave is magnificent, but it will also make you feel like you’ve walked to the edge of the earth and back. The passage is absurdly, almost comically huge – the kind of space that makes you wonder if whoever designed it was showing off. But size comes with effort. Bring water. Lots of it. You’ll thank me when you’re not trying to drink your own sweat halfway through.

It’s a limestone labyrinth that’s not dotted with lights or lamps. The walkway itself is well-maintained but the cave is dark. Pack a torch. Or at least ensure your phone has enough battery to light your way back. Because stumbling out of a three-million-bat cave in pitch black? Not the flex you think it’d be.

If you want the full “sky collapsing into bats” experience, plan your visit between mid-May and mid-October. During the colder months? They’re basically hibernating – which is nature’s polite way of saying they’ll be doing absolutely nothing worth flying across the world to see.

June brings the pitter-patter of tiny wings—baby bats enter the chat. By July and August, the nursery is in full swing, with the newest generation learning the family business of turning dusk into chaos. This is peak bat season, numbers-wise.

It’s obnoxiously, record-breakingly, big. By area, it’s the largest cave chamber on the planet. By volume, it settles for silver – coming in second after China’s Miao Room. You’ll find this spacious wonder tucked inside Gua Nasib Bagus, which translates charmingly to “Good Luck Cave”. The whole operation is nestled within Gunung Mulu National Park in Sarawak, Malaysian Borneo, where the jungle does its thing and the limestone just… waits. For millions of years.