Caverns are types of caves that have most of their open spaces located underground. Various passageways sometimes connect caves as a result of the weathering of rocks. Caves are hollow areas that are sometimes located within hills or mountains, and they have one or more openings.
Caves and caverns occur naturally, and the two terms are often used interchangeably. Volcanic activity, microogranisms, pressure, water erosion and chemical actions contribute to the formation of caves and caverns. Sea caves, sometimes filled with water, are found along the coasts of oceans and seas. They are created by tidal activity that constantly weakens and erodes the rocks located there.