The underground exploration is exciting, but a bit scary and dangerous. First, you may freeze there. Even though it was the middle of summer, it was about 8 degrees inside. We were aware of that, so we took warm clothes. Falling rocks are another problem. When you see piles of stones that have fallen from above, your imagination sees worst-case scenarios. But when we found a lot of stuff, we realized that it was worth it. After digging the tunnel, there was left a fan that is still rusting. The tunnel is supported by rusty iron struts that color the surroundings red. We also noticed numbers on the concrete slabs that perhaps indicate the distance from the entrance. We also found something that made us shiver unpleasantly – yellow rubber boots for children.