Ключевые слова: abandoned, adit, cave, cavern, coal, concrete, corridor, danger, dangerous, dark, decay, deep, derelict, digger, dirt, dirty, dungeon, exploration, industrial, industry, inside, iron, limestone, lining, metal, metro, mine, mine exploration, mineral, mining, mystery, old, ore, passage, prospecting, rail, railroad, railway, rock, rust, rusty, shaft, subterranean, trolley, tunnel, underground, underpass, urban, water,