Jomblang Cave is one of Yogyakarta's hidden treasures. A little off the beaten tourist track, descent into Jomblang involves being a manpowered rope lowering 60m down into an ancient sinkhole. It's enough to make even the most adventurous get butterflies in their stomach, especially when looking in from the top and seeing only a thicket of tropical forest.
Jomblang is a two-hour drive south-east from Yogyakarta. Only one tour is run a day - 10.15am every day, and only a maximum of 60 people are allowed in at each session to preserve the system's fragility. I arrived early at 9.30am in order to have time to rest before descending into the underworld.
I am hooked up to a sturdy harness and equipped with a helmet. Luckily, I've chosen to wear my North Face hiking boots today - they're waterproof, which will come in handy walking through wet mud (it rained yesterday) and inside the cave, through which an underground river runs. Those without waterproof boots are given rubber Wellingtons. Our harnesses are checked and double-checked to be extra secure, and before I know it I've been asked to step right up to the side of Goa Jomblang to be hooked up to the manpowered rope pulley system.
Trust is the hard part - it's a 60-metre drop, and it takes everything I have not to look down before I feel safe sitting in the harness.
It takes a while before the rest of the group has been lowered into Goa Jomblang. Once we are all ready and accounted for, a short five-minute trek takes us to Goa Grubug. The trek is short but I'm glad I have my phone, because once inside it is pitch dark and deathly silent. The floor is muddy and the dirt is compact, sediment from where the river that carved this cave used to run. Someone once built a pathway through this cave, but so many have walked over it that dirt has nearly obscured the steps entirely.
Grubug and Jomblang are part of the same cave system, so when someone tells you they're going to Jomblang, what they really mean is that they're going through Jomblang for Grubug.
The underground river that runs through this system is what is causing this extreme humidity that makes water condense on everything. It runs through the system and exits at Kalisuji, where I will be headed afterwards; the water is mineral-rich and has formed, over millions of years, massive rocks of limestone. Water is dripping down from every surface.
We stay here for an hour and a half, milking our time here for everything we've got. Jumping up and down the limestone formations (boots off when climbing on these delicate structures), taking endless pictures of the skylight above us, and exploring what of Grubug we're allowed to.
The time passes quickly, and before we've had time to catch our breath it's already time to head back out of Jurassic World. Most of us have mud-stained clothes, from climbing and falling over and into the wet mud. We're hooked up to our harnesses again and lifted back out of Jomblang.
After a packed lunch, my driver takes me fifteen minutes away to the nearby Kalisuci for river tubing. This is a welcome respite from the humidity and sweat of the cave. However I have carelessly forgotten to bring extra clothes with me - for some reason, I didn't quite put "river tubing" and "getting soaked" together! Luckily, nearby stalls sell extra clothes for a song, so I quickly pick up some extras.
At the river, we are geared with a life-vest and padded like babies. We have shin, knee and elbow protectors, as well as helmets. It isn't until I get to the river that I understand why - once in the tubes, we keep knocking into the sides of the cave wall as the current controls where we go.
This is easily the most fun I've had during my entire stay in Yogyakarta. We are soaked through and everyone is playing, splashing water at each other, all the time while going through this spectacular river-carved cave.