Beneath the dense canopy of Borneo’s rainforest lies a hidden world, invisible from the surface. A colossal underground chamber vast enough to fit 40 Boeing 747s lined up side by side.
This is the Sarawak Chamber—one of the largest subterranean spaces ever discovered by humans, a geological wonder that humbles all who enter.
A Hidden Cathedral of Stone
The Sarawak Chamber is located within Gunung Mulu National Park in Sarawak, Malaysia—a tropical rainforest park that has been designated a UNESCO World Heritage Site.
It was first discovered in January 1981 during the Mulu’80 Expedition by a British exploration team. Three explorers—Andy Eavis, Dave Checkley, and Tony White—found the cave after following a river that led them toward the face of a mountain.
From the outside, no one would suspect that behind the narrow crevice of Gua Nasib Bagus (Good Luck Cave) lies a breathtaking natural space. Upon stepping into the Sarawak Chamber, awe is immediate and inescapable.
The chamber feels boundless, its dimensions staggering: 600 meters long, 415 meters wide, and nearly 80 meters high. With a total volume of 12 million cubic meters and an unsupported ceiling spanning 300 meters, Sarawak Chamber holds the record as the largest known enclosed space on Earth.
In imperial units, that’s about 2,000 feet long, 1,400 feet wide, and nearly 500 feet tall—enough to make anyone feel as small as dust.
For scale, the Sarawak Chamber is more than twice the size of Wembley Stadium in the UK!
Trek to the Earth’s Heart
Reaching the Sarawak Chamber is no easy feat. The journey begins at Camp 1, where visitors spend the night before embarking on a three-hour trek. The trail is demanding and requires good physical condition.
After traversing a thick rainforest slick with tropical rain, the route continues along a river flowing from gaps in the limestone rock. What starts as ankle-deep water gradually rises to chest level, often requiring trekkers to cling to ropes bolted into the cave walls by previous explorers.
Along the way, the beam of your headlamp dances across misty water spray, while the sounds of birds and bats echo through the dark. Some birds even perch briefly on your chest—as if acknowledging your presence as part of this extraordinary space.
After more than a mile of wading through rapids and sharp rocks, the river finally disappears—and you stand at the threshold of the Sarawak Chamber.
A World Without Time, Without Light
The moment you enter the main chamber, all sense of scale begins to dissolve. Your headlamp reveals only a small fraction of the colossal dome above. Up and down lose their meaning—in total darkness, the world could just as easily be upside down.
Here, even the concept of time blurs. There is no sun. No dusk. Only snacks and a cup of tea serve as markers for the passing of “days.”
Sarawak Chamber is a natural cathedral, sculpted over millions of years by the slow dissolution of limestone. Within it lie underground rivers, curtains of calcite formations, and massive stone walls that host rare ecosystems.
Some species of bats and insects have even evolved to survive in complete darkness.
Science in the Belly of the Earth
Far more than an extreme travel destination, Sarawak Chamber is a vital subject of scientific study. Geologists, biologists, and climatologists regard this cave as a living laboratory. Its complex, sealed-off structure allows researchers to examine ancient climate changes, rock formation processes, and the fragile biodiversity that has adapted to this underground world.
One legendary cave researcher, known as “Mad Phil,” is famed for climbing cave walls others wouldn’t dare attempt. Alongside Eavis, he believed the Sarawak Chamber’s ceiling might conceal hidden corridors—like secret attics in a vast, ancient house.
The Spell of Silence
At night—or more precisely, during “rest time”—explorers roll out sleeping mats on flat rocks, hang their wet socks to dry, and gaze up at artificial stars: the glowing eyes of spiders reflecting light like gemstones, some as large as a palm.
The air inside the cave is warm and damp, as if the darkness itself were a mist wrapping around everything.
And though the cave seems determined to swallow all light, the memories carried out of Sarawak Chamber shine vividly. Moments when a camera flash sweeps across the cavern dome, when a bird lands on your chest, or when the sound of water echoes through stillness—these become unforgettable experiences etched into the soul.
