The following is a list of the world's 10 longest caves per length of documented passageways. Many passageways are still being discovered; this list is based on the latest verifiable data.
Caves are found around the world. The largest form in areas of karst landforms whose rocks erode easily and create caves. Preferable conditions for cave formation are adequate precipitation, enough plants and animals to produce ample carbon dioxide, and a landscape of gentle hills which drains slowly. The highest concentration of long caves in the world are found in the Pennyrile of Southern Kentucky, USA, in the Black Hills of South Dakota, USA, and in the Yucatán Peninsula, Mexico.
|Rank||Cave||Length||Location||Discovery||Associated parks, protected areas|
|1||Mammoth Cave||400 mi (643.7 km)||near Brownsville, Kentucky, United States||1791||Mammoth Cave National Park, also a World Heritage Site and International Biosphere Reserve|
|2||Sistema Sac Actun / Sistema Dos Ojos||308.4 km (191.6 mi)||near Tulum, Quintana Roo, Mexico||1987||none|
|3||Jewel Cave||257.5 km (160.0 mi)||near Custer, South Dakota, United States||1900||Jewel Cave National Monument|
|4||Sistema Ox Bel Ha||242.4 km (150.6 mi)||near Tulum, Quintana Roo, Mexico||1996||southern parts in Sian Ka'an Biosphere Reserve|
|5||Optymistychna Cave||236.0 km (146.6 mi)||near Korolivka, Ukraine||1966||none|
|6||Wind Cave||223.8 km (139.1 mi)||near Hot Springs, South Dakota, United States||1881||Wind Cave National Park|
|7||Lechuguilla Cave||217.3 km (135.0 mi)||near Carlsbad, New Mexico, United States||1900||Carlsbad Caverns National Park|
|8||Hölloch Cave||200.4 km (124.5 mi)||Muotathal, Switzerland||1875||none|
|9||Fisher Ridge Cave System||191.7 km (119.1 mi)||near Cave City, Kentucky, United States||1981||Mammoth Cave National Park|
|10||Gua Air Jernih||189.1 km (117.5 mi)||Miri, Sarawak, Malaysia||1978||Gunung Mulu National Park, also a World Heritage Site|