Subterranea (geography) - Subtopics

Underground lakes Subterranean rivers Subterranean fiction Subterranea of Bosnia and Herzegovina Underground construction Trenchless technology Rock-cut architecture Chthonic beings Subterranea of the United States Subterranean warfare Subterranean waterfalls Ancient Roman tombs and cemeteries in Rome Burials Mines Sinking rivers Underground nuclear weapons testing Urban exploration Semi-subterranean structures Underground mining Subterranea of the United Kingdom