A mine fire or coal fire is the underground smouldering of a coal mine. Such fires have economic, social and ecological impact.
Mine fires can burn for very long periods of time (from months to centuries), until the seam in which they smoulder is exhausted. They propagate in a creeping fashion along mines shafts and cracks. Because they are underground, they are extremely difficult and costly to reach and put out. There is a strong similarity between mine fires and peat fires.