Jungle presses in on both sides. A one-metre python dangles from a branch like a lost scarf awaiting its owner's return. We watch for 10 minutes. The snake watches us watching it.
It suddenly uncoils its powerful body, slithering languidly from view, deeper into the dense Borneo jungle. Tropical ferns and vines glisten moistly, reminding me of a deafening downpour ending moments before this boardwalk stroll began. Our destination: Deer Cave, the most visited diversion in Gunung Mulu National Park. A World Heritage site, the park attracts holidaymakers to Sarawak, one of two Malaysian states on the Southeast Asian island of Borneo.
There are three ways to reach this remote gem. The easy way in, chosen by almost all tourists, is by air (with several half-hour flights each day from Miri, a modern and mid-sized city).
Two alternatives are undeniably memorable: jungle river ferries - the preference of some backpackers - or a challenging land-and-water route for the fit and intrepid, combining four-wheel-drives along former logging trails with hiking and river boats.
From a treetop-level bird "hide" - for discreet observation of avian life - I gaze upon a stunningly beautiful jungle backdrop. A big-beaked hornbill, a member of one of the park's eight hornbill species, sits on a nearby tree branch. Sarawak terms itself "land of the hornbills", with these strange-looking creatures plentiful in the park.
I wander along a 480m jungle canopy walkway, which park officials call earth's longest tree-based crossing.
The rainforest and its rivers support an array of wildlife: bearded pigs, pangolins, crocodiles, squirrels, sun bears, barking deer (and other antelope types).
Next day, I sample a chunk of Head Hunter's Trail, one of many hiking trails and named for a long-gone custom of beheading enemies. In the evening, a night cruise up the Melinau River has guides identifying insects, frogs and nocturnal birds.
But what attracts most visitors is a collection of caves. This 52,000ha reserve is pockmarked by spectacular cavities - including Sarawak Chamber, the world's largest cave, which boasts an interior so cavernous that 40 jumbo jets could park inside.
But here's the catch. The Sarawak Chamber is one of several hard-to-get-to "wild caves" without lighting or pathways.
Park authorities admit only those proving they're experienced cavers (sometimes with letters from foreign caving clubs) and agreeing to be accompanied by guides. Gruelling hikes often precede visits to "wild caves" with narrow crevices and tunnels.
Four so-called "show caves" are an altogether tamer - and more popular - diversion. Exploring is eased by boardwalks and lighting.
That's why I find myself on one boardwalk, traipsing through the Borneo jungle to Deer Cave, by far the most visited, where I transfer to another and venture inside.
Continue reading at: A gem in the Borneo jungle.