Collapse
Perhaps the most common abandoned mine danger is collapse. Over time, the mine begins to fill itself, closing in the tunnels that miners dug in the past. Being in an abandoned mine when the rock begins to shift can trap explorers in the shaft or even kill them with a rock fall.
Falling
The openings to mine shafts range from 26 degrees to 55 degrees. Even at the lower end, the incline leading into a mine is sharp. Falling into the shafts presents a danger for two reasons. First, few people can regain their footing while falling, and falling into a mine shaft can mean landing in or on dangerous rock. Second, shafts can be hundreds of feet long, making a fall to the bottom potentially fatal.
Noxious Gas Exposure
Three dangers arise from gas or fumes in abandoned mines. The first problem is not having enough oxygen. While experienced explorers may carry oxygen monitors, knowing when there is not enough good air still requires some guesswork. Equipment and explosive devices used in mines can release and then trap carbon monoxide and other potentially poisonous gasses, which can sicken or kill modern explorers. Mine shafts often have pools of water at the bottom of them, and these pools absorb the chemicals in the air, creating significant concentrations of noxious fumes around them.
Explosives
Miners once used dynamite sticks to blast areas where they wanted to create an opening. Many miners left these dynamite sticks in the mines, and they are still there today. The danger of a sitting stick or block of explosive going off is slim, but adventurers who pick up these explosives put themselves in danger.