Ключевые слова: abandoned, adit, catacomb, cavern, channel, coal, collector, concrete, corridor, dark, deep, derelict, digger, dirt, dirty, drainage, draining, exploration, flood, flow, flowing, industrial, inside, interior, lost, mine, mineral, mining, old mine, ore, passage, pollution, resources, river, rock, sewage, sewer, sewerage, stream, subterranean, toxic, tunnel, underground, underpass, urban, vaulted, waste, wastewater, water,