Grubug Cave is more popular as Luweng Jomblang-Grubug. “Luweng” is a Javanese term for a vertical cave. While Jomblang-Grubug is used as a name since this cave has 2 entrances: Jomblang and Grubug. Both entrance connected by 200 meters cave channel.
Luweng Jomblang-Grubug is located at Dusun Jetis, Semanu, Gunung Kidul, Yogyakarta, Indonesia. It is one of hundreds of karst caves situated in Gunung Sewu karst area, also called PaWonSari (Pacitan Wonogiri Wonosari).
We are more frequently reaching the underground river through Luweng Jomblang. The lack of equipments made us seldom descend Luweng Grubug. To descend Luweng Grubug, cavers have to utilize 100 meters long of kernmantel . While for Luweng Jomblang, 50 meters of kernmantel is enough to descend in the route A (Jomblang’s highest route).
One week ago we succeed to get a brand new rope. A hundred meters of kernmantel dynastat which I really needed since several months ago to climb Raung mountain crater from Glenmore side. Not taking a long time to try new equipments, a week later we define our trip, Luweng Grubug.
The raindrops from Jogja keeps falling until one and a half hours later in Wonosari. In a motorbike trip to Gunung kidul karst hill. Luweng Grubung is situated in Semanu, Wonosari. In a village corner surrounded by teak wood forest on the karst. Muddy path ( a mixed of mud and macadam) was really something that complicate the trip 30 minutes before reaching Luweng Jomblang.
We arrived in a resort area of Luweng Jomblang in a wet condition. The area itself is something luxurious amid the dark of cassava field and teak wood forest. There was nothing like this 10 years ago, since the place was very dark and rarely visited. Only cavers who visited the place. But now it’s different.
We get along very well with the resort guards like Nafick and Danang since this place is like our playground. They are members of Hikespi. In that early morning, Danang welcomed us in one of the resorts. The resort area itself has not been launched officially, still waiting for some improvement here and there. Some improvement that I think will make the place amazing if they are well-implemented. Yes, a big pond for diving and swimming, of which water was pumped up from the underground river 100m below luweng Grubug. Our greatest salute for Mr Cahyo, who is now intensively train his team with diving ability in order to develop the resort complexes of Luweng jomblang-Grubug.
That night, we were welcomed and pleased to stay in a cottage which has been prepared and assigned for adventurers. It is a beautiful humble 27 squares meters open cottage made from bamboos located close to Luweng jomblang entrance.
I barely couldn’t sleep that nigt, my juniors was very noisy talking and joking a whole night. But I understand and tolerate them, because things like that we often do, even in the middle of tension situation.
After 7 aclock in the morning, it was clearly seen that in front of the cottage was a giant hole with 40 meters in diameter and 50 meters depth. 8 Cavers has gathered in the cottage after half our ago we have had our dinner together at the edge of jomblang cave entrance hole. We were then having a short brieafing before installing the anchor.
First, we had to install the anchor at Luweng Jomblang. We chosed the A track, which was exactly located in front of the cottage. As our plan, we would use this track to ascend from bottom of the cave this afternoon. We would ascend about 40 meters high in this track. Actually there is an easier track, the VIP track, which are widely used by the beginner (20 meters ascending-descending, 20 meters scrambling ). But we prefered the track A, the more difficult track.
The second anchor we would installed was at Luweng Grubug, about 200 meters west of luweng Jomblang. We would descend as high as 90-100 meters from the top of the entrance hole of luweng Grubug to the underground river at the bottom of the cave. This track is not recommended for beginner.
Anchoring, the security of a caver was entrusted on a rope which is hold by a gold anchor and 2 silver anchor (it has become a standard here). In the karst area, an anchor can be tied in an aperture penetrating karst rocks, teak tree trunks, or a solid tree roots. Natural anchor is more nature friendly than have to create an anchor by making a hole on karst rocks.
Each team basically has a standard installation of an anchor according to their customs methode. Whether it is the knot-knot rope, the use of carabiner, sling and so forth. But one thing is for sure, make people to feel safe hanging is mandatory for a caver. Caver is hanging at a height of 100 meters will always trust the equipment he uses and of course going to trust his fellows who has assigned above the anchor.
In track A, the anchor was installed on a sturdy tree trunks on the edge luweng Jomblang. The rope which we used here was the 50-meters rope. Be careful when installing an anchor here, make sure you are in a safe position from the hole. Make a safety on the body that hooked onto the trees.
Track A has been safely prepared , we turned to go toward Luweng Grubug and carried all descending equipments.
Karst is a fun playground if you are also in a safe and comfortable condition.
To be at the most beautiful places on this planet, there are always sacrifices for it. One of them is sacrifice to conquer your fears. Be brave!
Luweng Grubug, when seen from a satellite, it is an appearance of black dots that are smaller than a black dot on the south east side (Luweng Jomblang). This Luweng has an aperture entrance hole diameter of 12 meters. If we stand at the edge of the hole, the roar of underground water flow 100 meters below luweng would be heard. But we can not see it. Luweng Grubug is enclosed by stems and twigs of trees arount its entrance hole. So if the sun light falls down to the underground river, would cause a tremendous effect on the battom of the Luweng. Effect of sunlight berpendarnya materialize along the lines of 80-100 linear feet from top to bottom. This is one natural phenomenon that became a trademark in speleologi activity. The photographers say, the effect of ROL (ray of light) light.
Yet, the sun has not perpendicular to the earth
We have arrived at the edge of luweng Grubug. The team would be ready to descend down along the 100-meter rope to the bottom of the cave. The length of rope that would be left at the bottom was only 15 meters long and used to anchor at the top along the 3-meter, thats mean cavers would come down on a rope as long as 80-85 meters from top to bottom.
Anchor would be tied at a teak tree and 2 holes on the rock in the front left and right. So 3 pieces of the anchor line would form a triangle. A strand of short kernmantel would unite them before the the 100-meter kernmantel dynastat tied at the intersection of these three anchors.
There are 7 people would go down the Luweng Grubug, while a caver would guard at the top. They aould switch to lane A of Luweng Jomblang in the afternoon when ascending . The order of cavers who would descend to to the bottom has been determined. And in the middle of the sequence, there would be a break to transfer the SRT set from bottom to top.
The main tension of a caver was several minutes before he went down and located his body at the lips of the hole. Just after he was hanging on the rope, he would automatically return to normal psychological. A moment of panic would happen on the way down if he thought hes used unsafe tools. Yes , all fear was only in his mind alone. The higher the aperture, the higher the sense of panic if indeed hes very easy to panic-stricken. Then, hold the two main points. Believe in the tool that has been installed, both in body and in the anchor. Then trust your friends team mates.
Before a caver went down to the bottom, he would install equipment on the body. Other team members had to double check it again, it was very possible of installation errors. For examples , the harnest was untigten, carabiner that has not been locked, the Crawl that was installed upside-down, untight installation of the strap on the helmet, an inverted mounting rope on the descender and so forth. And these errors can be performed by an experienced caver. So, double check to each installation of equipment was a must.
During descending, took a break every 5 meters down. Do not be too hasty, because the effects of excessive heat could injure your hand. Made a gentle stop because when you brake suddenly, the rope would be elastic so that you would bounce up and down.
A caver normally would take 7 minutes to descend along the 80-85 meter. Water droplets would fall from above. All around us was a circular karst cliffs. Below, gourdam and Flowstone dominant among the winding river. From 100 meters above, it was still shrouded in fog, but on the way downside the landscape has become increasingly apparent. The room below was widened.
One by one, the team started descending down the luweng Grubug. Enjoy!
