If you're here in Dieng Plateau (Central Java) , take note that the volcanic craters are still active. If truth be told, Indonesia has the world's highest density of volcanoes with 500 of these pot boilers located in a region known as the "Belt of Fire" . Of these, 128 volcanoes are active and 65 listed as dangerous.
Over here in Dieng, more than 80 people were killed the Sinila crater belched out a cloud of poisonous gas. The latest eruption was as recent as 2003, when Sileri crater started pouring out lava.
So, as a precaution, do this before visiting any craters in Dieng:
1)Ask the locals if there are any recent volcanic activity
2)The craters in Dieng have no protective fencing ( this is not Yellowstone National Park), prep your kids and warn them about the possibility of being fondued alive.
3)Don't go too near the boiling mud holes ( DUH!)
They call it Goa Jimat, but the old Dutch name is more apt: Dodendal = Death Valley. It is an enclosed valley with volcanic vents at the bottom which release carbon dioxide. So it is hazardous to venture down in the valley, unless you have brought an oxigen mask.
Several years ago, after an earthquake, the carbon dioxide overflowed killing scores of villagers fleeing from the earthquake. The event is remembered in the video which they show at Dieng Plateau Theatre.
There is no sign pointing to Goa Jimat, no doubt intentionally. Yet it is easily visited, just a little side trip on your way to Candradimuka crater. Follow the road until you pass Kepakisan and a bridge at the lowest point in the road. A little distance past the bridge there is a small parking south of the road. On the other side of the road a footpath through the fields brings you to Goa Jimat. Keep to the left climbing up. It is not far, but the path may be overgrown.
Be careful when you walk around the craters, some parts of the soil are thin, so you can step into a crater, so make sure you find a guide.