That part of a cave environment that lies or once lay below the water-table. Also refers to the processes that act within the phreatic zone.

Cave passage formed when full of water

of or relating to ground water

Cave passage formed when completely flooded. Usually round and undulating.

A term used to describe speleogenesis that occurs at or below the level of the water table. Passages formed phreatically are typically horizontal passages, rounded and smoothed by the passage of underground water. "Fossil trunks" are always formed phreatically, at least initially.

Formed under water by chemical solution. Phreatic passages are not controlled by gravity flow and so may rise or fall at will. Most phreatic passages are rounded or elliptical in cross section

The term phreatic is used in geology to refer to matters relating to underground water below the water table (the word originates from the Greek phrear, phreat- meaning "well" or "spring"). "Phreatic surface" is a synonym for "water table."