Stepping out of the pint-sized airport in Mulu is like being vaulted straight into a nature documentary. We’ve already been on Borneo for about two weeks, but it isn’t until we’re walking the 1 kilometer stretch of road from the airport to the grounds of the national park that I really, truly feel that we have arrived. The rest of the country has been nice and given me glimpses of the wildness I came here expecting, but now I am surrounded by so much natural beauty that there can be no confusing where I stand.

As we walk to the park (having stubbornly refused to pay the exorbitant taxi fees when the day is so lovely, our surroundings so pretty, and the distance so insubstantial), the plump marshmallow clouds in the sky offer little coverage from the blazing heat of the sun, and the pounded dirt road we follow is hemmed in on either side by lush meadows, the long grass lazily swaying in the breeze like a hula girl’s skirt, green as far as the eye can see. Gazing up, I lose myself in the endless blue ocean of sky above me, feeling the same slightly vertiginous thrill I do when preparing to plunge into deep water and the clarity of the water and its natural magnification properties have thrown my depth perception off. I wonder if it’s possible for the sky to make me feel a little drunk, just by being so big and so blue. Maybe it’s sun stroke sneaking up on me, but I’m pretty confident that I’ve never seen a sky one could so easily get lost in as the one currently draped over this little patch of the world. Apart from the excited trill of my voice exclaiming about how beautiful everything is, the space around us is silent and sleepy from the heat of a day that has just barely begun.

Passing onto the grounds of Mulu National Park, we cross a rickety suspension bridge below which a frothing river rages, and register at the park headquarters. Along with picking up the key to our lodging, we also pick our tours and activities for the next three days. Mulu is famous for several things, but by far the attraction that garners the most travelers is the grueling multi-day trek to a series of jagged limestone peaks known as The Pinnacles. Knowing our limits, we decide that we will be satisfied with a few of the less challenging sites on offer and sign up for tours of the park’s most famous caves as well as a canopy walk that will allow us to take in the rainforest from up in the tree tops.

Details and paperwork sorted, we head to our room for the next three nights—we’re staying in the park’s dormitory, and the building feels a bit like I imagine you’d find at a summer camp for scrappy orphans. If that sounds unpleasant to you, I assure you it isn’t, as the rooms within have large windows (with quality screens), ceiling fans, and no more than four cots to a room so as to avoid the dreaded “sardine” syndrome that is all too common in low-budget communal bedrooms; other than the lack of doors on all the rooms, there’s really not much to complain about. We manage to find a room near the back with only three beds and claim two of them with our stuff, hoping that any interlopers will feel awkward about having to room with a couple and bunk elsewhere. Given that we’re each only paying $13US for our room, we were expecting a lot less; it is clean, the beds are comfy, the other people in the building seem to understand that dorms should be quiet spaces to foster sleeping, so we can’t really ask for much more.

We nap for a little bit and grab some lunch from the canteen before moseying over to the meeting point for our tour of Lang and Deer caves. The group is small, just ourselves, our gregarious guide Jesper, and a Dutch girl named Esther, one of those formidable people who runs marathons and actually enjoys inflicting pain on her body. She has recently returned from summiting the Pinnacles and the trek has taken a real toll on her body as she can barely push herself past a feeble hobble… which means she perfectly matches our own normal pace! We’re all a bit worried because we’ve been told it’s a three kilometer hike to the caves, but thankfully, the word “hike” turns out to be more than a little misleading. The entire route is either paved or on an elevated wooden walkway, is essentially flat, and not the least bit taxing. It may detract ever so slightly from the notion that we are roughing it in the jungles of Borneo, but I’ve got a good imagination and would rather have a relaxing stroll around nature rather than right through the thick of it, complete with leeches and other creepy crawlies.

The only downside to the path that I can see is that it is so obvious and easy to navigate that it makes the requirement that one have a guide supremely unnecessary and an obvious cash grab. Given that I would actually have to climb over barriers in order to stray from the path and get lost, I am a little bit annoyed, but Jessper soon pulls me out of my funk with his cheerful attitude and by pointing out adorable pygmy squirrels, which are from nose to tail, I kid you not, no bigger than the length of my middle finger (so, about 8 centimeters). Borneo: land of big open spaces and miniaturized animals… who knew?

The first cave we visit is Lang Cave, which is a bit like entering your grandmother’s attic… provided your grandmother has an attic and it is filled with stalagmites, stalactites, pygmy bats (See! More tiny animals!), swiftlets, and creatures that look like cobwebs but are actually carnivorous worms (as if cobwebs weren’t disturbing enough as they are!). We work our way through the cave, marveling at the many formations that have erupted from the cave due to the constant trickle of high salinity water on the limestone over the centuries. Lang Cave is highly atmospheric and just a little bit eerie, exactly the way I always imagined a trip to Borneo would be.

Next, we head to Deer Cave, thus called because deer were once attracted to the cave due to the high salinity of the water there. Why is the water so salty? Because of the high concentration of bat guano that falls into it! For that reason, Jesper warns us to keep the tops on our water bottles tightly sealed when inside the cave and we should probably refrain from looking up with our mouths gaping open in astonishment. Duly noted.

I’m glad Jesper gave us that warning because every so often we do things on this trip that are so surreal that I do stand there gawking like I’m doing my best slack-jawed yokel impression. Entering Deer Cave is definitely on that list of mind-boggling experiences. It is the largest cave system in the ENTIRE WORLD, and like the meadows and sky leading up to that moment, it is just so MASSIVE it truly defies comprehension. Standing there, I feel like a grain of sand in a giant’s palm, completely insignificant and so very, very tiny.

As we make our way through the massive cavern, we hear the leaf-thin wings of millions of bats fluttering above us, echoing off the stone. I risk a quick peek or two upwards hoping to catch some glimpse of them, but they are so high up and the cave is so dark it is like trying to peer into a black hole. One upside to the complete absence of light is that it allows us to see some nifty phosphorescent centipedes that continue the trend of Borneo blowing my mind as they actually glow green as they writhe and undulate in Jesper’s palm (all the while defying any and all attempts to capture them in photos, naturally).

We only see a fraction of Deer Cave, but the place is so huge, it takes us nearly an hour to explore it anyway. Jesper ushers us out late in the afternoon to go sit by one of the entrances in the hopes that come dusk, we’ll be able to witness a mass bat exodus where the creatures rouse themselves from slumber and take the sky en masse to hunt for bugs. Alas, as we are at the tail end of the rainy season, Jesper warns us that it is likely too cold and the impending rain (of which we detect not a trace) will keep the bats safely sequestered inside the cave.

We wait for an hour but apart from a few swooping swiftlets cutting graceful arcs through the air, Jesper’s premonition of quiet skies proves true. That evening as we are tucking ourselves into bed, an ominous rumble shakes the air around us, prefacing the fat drops of rain that soon begin to tumble. Clearly Jesper and the bats were right about the weather! We drift off to the susurrus of rain in the trees, its gentle tap-dance across the roof a soothing lullaby after the day’s sweaty adventures.

The next day, we wake up early feeling eager for another day of adventuring. We have signed up for a tour of Wind Cave, which can be reached by foot or by boat… we immediately make our way down to the river and step into a small canoe that is soon nosing its way into the jungle. En route, we are taken to a tiny tribal village that sets up a small market beside the river—it is meant to give us a taste of the local way of life, but it is very quiet and mostly just serves to make us feel awkward and guilty because everything that is on display has clearly been done with cash-happy tourists in mind. Our guide for the day is actually from the village originally and tells us that many of the people trying to sell us things have come from the surrounding woods and they come here for the small chance of selling something to tourists and making some money… it is their only potential source of income.

I am not necessarily upset that these locals have decided to try to make tourism work for them and try to get a piece of the national park’s pie, but there is a quiet desperation to the place that makes me think that tourism has disrupted the ecosystem of the area as the locals have perhaps come to rely on tourist money more than they should. It is an unsettling start to the day and a good reminder for us as to why we normally avoid package tours where shopping stops are routine; I have become very good at cutting out unnecessary shopping in our lives, justifying our frugality by saying we don’t need most of what these people are selling. But what if they need us to buy? Our group of five are the only people at the market, so the pressure to buy something is immense, and although I really do not want anything, Tony & I elect to purchase a few small key chains that we can use as zipper pulls on our backpacks (agonizing over the fact that we only purchase from one woman when there are 12 other sellers who go without).

Our small purchases in hand, we get back into our tippy little boat that dips worrisomely low in the water with five westerners inside it (even if one of them is a five-year-old boy). Our guide revs the engine and we zip along the river and feel incredibly intrepid although we are doing nothing more than sitting there. We are told that the river is normally crystal clear, allowing you to see all the way to its bottom, but the previous day’s rain has turned it to the opaque shade of milky coffee.

Unexpected diversions aside, our next stop is Wind Cave, which despite its name, is not windy at all, and is instead stuffy and close inside. We brave the stifling heat to walk through its tunnels lined with moonmilk and wonder how a place that seems ripped straight from a video game can exist naturally on our planet. As we enter the section the cave called the King’s Chamber, Tony and I whisper about the likelihood of treasure chests and Skyrim’s draugers, our stifled giggles echoing off the high walls of the chamber.

In one of the biggest caves in the world

Back outside, we pile into the boat and get on our way to Clear Water Cave, which can only be reached via 200 steep steps. We figure this is penance for skipping out on Yamadera when we were in Japan and get to work. When we reach the top, we are rewarded with an expansive cave that is reminiscent of Deer Cave, but for a huge river running straight through the middle of it. It also features some beautiful natural skylights and some very cool elevated walkways.

Due to the murky state of the river, we demur at suggestions of jumping in for a cooling swim, and instead head back to the park headquarters to grab some lunch. Then it’s off to the heart of the forest where we do the Canopy Walk, a tour that is supposed to take about 2 hours but winds up only taking our group 45 minutes largely due to the fact that half of the people signed up are terrified of heights and can’t stand to be on the rickety rope bridges 30 meters above the forest floor any longer than they have to. Why we did not consider that Tony’s crippling fear of heights might be problematic when we signed up for this tour, I cannot say, only that neither of us seemed to think it would be an issue at all until we were actually up in the trees. Tony is light-headed and terrified for the entire tour, but he is a trooper and makes it through the whole circuit, though sadly gets little enjoyment from it. I think it’s quite exhilarating to be so high up, and although I’m disappointed we don’t see any wildlife, the views from on high are spectacular.

As we descend from the treetops back to solid ground, our adrenaline begins to ebb and our energy levels slump accordingly. We stroll lazily towards Deer Cave and hunker down with a sleeve of cookies to tide us over as we wait once more for the bats to grace us with their dinnertime flight. Alas, tiny drops of rain begin to smatter us during our vigil, and so all we get for our patience is the occasional tendril of bats, flitting about like shimmering funnels of smoke, something akin to the smoke monster from Lost. It may not be the full-blown exit, for us or the bats, but it is still quite cool to watch their flawless choreography as they twirl about in perfect synchrony, a gestalt cloud of activity.

As a bonus, here’s a little video (set to groovy music) of the bats zipping around the sky!

We spent three days at Mulu, nestled in the center of the park simply rejoicing at being surrounded by so much glorious nature. As someone who considers herself a city girl through and through, it was something of a revelation. We rejoiced in being outdoors in unadulterated, unbridled Borneo, walking anywhere between 9 to 10 kilometers each day in our explorations, and then relaxing late into the evenings with books and ice cream and the nocturnal sounds of the forest chirping in symphony around us. Of the three weeks we spent on Borneo, I don’t think we ever felt like we were closer to its heart than we did at Mulu.

We only did a small sampling of the activities on offer at Mulu, and although we did visit its very best caves, we never did witness the epic bat exodus in its entirety. I guess that just means that one day we’ll have to go back. I can’t wait.