A cave or cavern is a natural void under the Earth's surface.[1] Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock shelters). Caves which extend further underground than the opening is wide are called endogene caves.[2][3]
Speleology is the science of exploration and study of all aspects of caves and the cave environment. Visiting or exploring caves for recreation may be called caving, potholing, or spelunking.