A plunge pool waterfall lake, a depression at the base of a waterfall created by the falling water scouring where it lands.
A plunge pool is a recreational water feature in landscape design, and constructed in gardens. They can be small-diameter swimming pools used for cooling off in warmer climates.
These plunge pools are built to the same specifications as swimming pools in regards to structural engineering, sanitation and filtration requirements. Their smaller surface and ease of covering reduce water loss through evaporation. Their popularity has increased with the modern needs of urban living.