Cruising out of Yogyakarta in the early morning, the warungs, rukos and drab grey buildings that belie the city’s eclectic spirit give way to a vibrant countryside. Our destination is Goa Jomblang, an enormous sinkhole located in Gunung Kidul, two and a half hours southeast of Java’s cultural heart. Accompanying me is Wono, a native Yogyakartan and former dancer.

As we get closer his enthusiasm ebbs and he bashfully informs me that he is only joining to be a good host. As the vegetation gets thicker and the roads rougher, we eventually reach a group of bungalows that mark our destination. We’re greeted by our expedition crew as we pull up, their English is as patchy as my Bahasa Indonesia, but soon we’re seated with steaming mugs of silty kopi in hand, awaiting our fellow spelunkers. The coffee has begun to work it’s magic by the time they arrive and we’re quickly equipped in what passes for our safety equipment; a construction helmet, gumboots, torches and a flimsy harness. Making our way down to the edge of the main sinkhole, Luweng Jomblang, we’re immediately struck by it’s size. Vines and trees trail over the rim and into the depths where eighty metres down a pristine forest grows, a self contained and still largely undisturbed ecosystem. Our attention returns to the surface, where only now we notice the mechanism for our descent: a small steel frame and pulley system leaning out into empty space. It is now explained to us, with Wono’s assistance, that the majority of the eight-man crew will be responsible for lowering us down on a rope by hand, while we do our best to avoid criss-crossing vines and rock-outcroppings. At this point I begin to seriously question the value of the experience. Wono is incredulous. Having come this far, we steel our nerves and are put in position.

After a final check the descent begins. Wono giggles in terror the entire way down, his eyes screwed firmly shut while I try to keep us clear of any snags. In just a few minutes that stretch for eternities we reach the bottom, where our guide Arif is awaiting us with a wry grin. Our companions soon join us and we proceed down a muddy embankment into the pitch black cavern that connects us to Grubug Jomblang. As the light fades we flick on our torches and press on into the darkness. A dim glow grows slowly in the distance and as we round a small hill, the mouth of the cavern comes into stark relief. We stop dead in our tracks. Shafts of thick, pure, white light pierce the cave. It’s mesmerising, but we know the real payoff lies just ahead. We reach the cave and somehow our eyes grow wider, our amazement deepens. An alien landscape confronts us. The light bounces off slick stalagmites and pools of water. Everything glows. We make perfect silhouettes, admiring the ‘light of heaven’.