Beside the mountain itself, the most amazing thing in Ijen is about the sulfur lake. This "Green Crater" has a lake made of 36 million cubic meters representing a solution of sulfuric acid and hydrogen chloride, the most powerful existing acids.

When visiting Ijen Crater, we can see the sulfur miners that collect and carry huge loads of pure sulfur up from the crater floor along a steep, rocky path in the middle of clouds of sulfur dioxide gas.

On the edge of the lake, therer are 4 tons of sulfur that can be collect daily. These lakes result from the mix of rainfall water with gases coming from the depths of the volcano.

The walls in Ijen Crater are having light ocher, but the water is turquoise with emerald reflexes. The water temperature is around 34 degrees Celcius with the sulfur bubbles floating on the surface and the surroundings are also covered by sulfur powder.

All around the area, the sulfur pours at the temperature of 120 degrees Celcius. It looks bright red trails which gradually solidify and turning to lemon yellow.

That turqoise lake is contain of 600,000 tons of hydrogen chloride, 550,000 tns of sulfuric acid, 200,000 tons of aluminium sulphate and 170,000 tons of iron sulphate.

The most incredible of this mining is, the miners that extracting the sulfur are working manually...yes manually! To increase the efficiency, the workers build kind of tunnels of stone and flowing plates to channel the sulful. The sulfur then leaks, cools down and solidifies inside these improvised channels, which are subsequently broken using metal piles. The recovered stuff contains 99 % sulfur. The sulfur is made into pieces, loaded in baskets and transported on the men's back outside the crater.