page_title: Subterranean river
section_title: Natural examples
hierarchical_section_title: Subterranean river / Natural examples
caption_attribution_description: Buna 10
context_page_description: A subterranean river is a river that runs wholly or partly beneath the ground surface – one where the riverbed does not represent the surface of the Earth. It is distinct from an aquifer, which may flow like a river but is contained within a permeable layer of rock or other unconsolidated materials. A river flowing below ground level in an open gorge is not classed as subterranean.
  Subterranean rivers may be entirely natural, flowing through cave systems. In karst topography, rivers may disappear through sinkholes, continuing underground. In some cases, they may emerge into daylight further downstream. The longest subterranean river in the world is the Sistema Sac Actun cave system in Mexico.
  Subterranean rivers can also be the result of covering over a river or diverting its flow into culverts, usually as part of urban development. Reversing this process is known as daylighting a stream and is a visible form of river restoration. One successful example is the Cheonggyecheon in the centre of Seoul.
  Some fish and other troglobite organisms are adapted to life in subterranean rivers and lakes.
  Examples of subterranean rivers also occur in mythology and literature.
context_section_description: There are many natural examples of subterranean rivers. Among them:
  In Bosnia and Herzegovina: Unac; Mušnica-Trebišnjica-Krupa/Ombla (Ombla springs out of huge cave near Dubrovnik, Croatia and after just ca. 30 meters empties into Adriatic Sea's ria called Rijeka Dubrovačka); Zalomka-Buna/Bunica/Bregava; Vrljika-Trebižat; Lištica-Jasenica; Šuica-Ričina
  In Bulgaria:
  Banderishka reka, subterranean section below Kutelo Peak, Pirin Mountain
  Struma River subterranean currents in Duhlata cave, Vitosha Mountain
  Negovanka River subterranean currents in Emen cave, Veliko Tarnovo Province
  Trigradska reka, subterranean section where Devil's Throat Cave and Trigrad Gorge, Rhodope Mountains
  The Camuy River located in the northwestern region of Puerto Rico is one of the largest underground river systems in the world.
  The Cross Cave system in Loška Dolina, Slovenia includes 22 subterranean lakes
  The Lost River in the Appalachian Mountains of West Virginia disappears underground and reappears as the Cacapon River
  The Mojave River in southern California flows underground in most places
  The Phong Nha-Kẻ Bàng National Park in Vietnam has an underground river flowing through its cave system
  The Puerto Princesa Subterranean River on the island of Palawan, Philippines flows underground before emerging into the West Philippine Sea 
  The Punkva in Moravian Karst, Moravia, Czech Republic  underground river flowing through cave system - Punkva Caves and Macocha gorge.
  The Santa Fe River in northern Florida drops into a large sinkhole in O'Leno State Park and reappears in the adjacent River Rise Preserve State Park, 3 miles (4.8 km) downstream.
  The Hamza River is an aquifer which flows beneath the Amazon River in Brazil and empties into the Atlantic.
caption: The cave of source of the Buna can be entered by boat and dived through a cave system serving as an effluence of the Zalomka.
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