Station: [7] Water pools

We have now arrived at the water ponds. This is not ground water.  When it rains, for example, the water seeps through small cracks and crevices in the rock from above.

Since we are about 30 meters below the earth's surface at this point, the water is sufficiently filtered so that it is clear and pure. You could even drink it. However, with a temperature of 5 to 6
degrees Celsius which is about 41 to 43 degrees Fahrenheit, it is not recommended for swimming.

The average temperature in the mine is at about 10 to 12 degrees Celsius, which equals about 50 to 53 degrees Fahrenheit  and remains relatively constant even in winter.
The air in the mine is very pure and dust-free, and the humidity is between 90 and 95 percent. Staying in the mine is therefore often a huge relief for allergy sufferers or for people with asthma.

The water also had an important function at that time. The miners would put wooden wedges into even the smallest cracks and gaps in the rock. Then, they would constantly dampen the wedges with the rain water. The wood would soak up the water, expand, build up pressure, and would slowly but surely burst even the hardest rock. This method saved the miners a lot of strenuous work, since they would otherwise have had break up open the hard rock by hand, with hammer and chisel. 

The ancient Egyptians also used this method over 3000 years ago to build the pyramids.