Subterranea (geography) in the context of "Freshwater"

Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mineral-rich waters, such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes.

Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of vascular plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive.

Caves or caverns are natural voids under the surface of the Earth and have been observed in other rocky worlds also (viz. on Mars). Caves often form by the weathering of rock and can extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock shelters). Caves which extend farther underground than the opening is wide are called endogene caves.

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.

A kiva (also estufa) is a space used by Puebloans for rites and political meetings, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, "kiva" means a large room that is circular and underground, and used for spiritual ceremonies and a place of worship.

Similar subterranean rooms are found among ruins in the Southwestern United States, indicating uses by the ancient peoples of the region including the ancestral Puebloans, the Mogollon, and the Hohokam. Those used by the ancient Pueblos of the Pueblo I Period and following, designated by the Pecos Classification system developed by archaeologists, were usually round and evolved from simpler pit-houses. For the Ancestral Puebloans, these rooms are believed to have had a variety of functions, including domestic residence along with social and ceremonial purposes.

In civil engineering a shaft is an underground vertical or inclined passageway. Shafts are often entered through a manhole and closed by a manhole cover. They are constructed for a number of reasons including:

• For the construction of a tunnel
• For ventilation of a tunnel or underground structure, aka ventilation shaft
• As a drop shaft for a sewerage or water tunnel
• For access to a tunnel or underground structure, also as an escape route

In the animal kingdom, a maternity den is a lair where a mother gives birth and nurtures her young when they are in a vulnerable life stage. While dens are typically subterranean, they may also be snow caves or simply beneath rock ledges. Characteristically there is an entrance, and optionally an exit corridor, in addition to a principal chamber.

In architecture, an area (areaway in North America) is an excavated, subterranean space around the walls of a building, designed to admit light into a basement. Also called a lightwell, it often provides access to the house and a store-room/service cupboard for tradesmen, such as a coal store vault under the pavement.

The term is most commonly applied to urban houses of the Georgian period in the UK, where it was normal for the service rooms, such as the kitchen, scullery and laundry, to be in the basement. Areas were commonly enclosed for safety reasons by wrought iron or cast iron railings, which became one of the principal decorative features of the astylar terraced houses of this period. Areas are also found in the English and French country house, where basements were popular in the 18th century as a way of accommodating service functions while allowing all four faces of a symmetrical Classical building to relate directly to its landscape setting, as at Mereworth Castle in Kent or The Abbey in Cumbria. Basements, and consequently areas, decreased in popularity in the 19th century, as attitudes to servants changed, although they continued to be constructed as service accommodation in urban settings where land was at a premium until the early 20th century. A suburban residential application can be seen at the Gamble House in Pasadena, California, to light the laundry and service areas of the expansive basement.