Subterranea (geography) - Subtopics

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