freshwater lens

   1. Body of fresh ground water found typically beneath permeable limestone islands or peninsular land masses in the tropics. The lens-shaped water body is bounded above by a water table and below by a mixing zone between fresh and saline ground water along the halocline. In the center of the lens freshwater extends below sea-level, and another set of springs exists where dissolutional conduits associated with the lower limit of the lens intersect the rock surface below sea-level [9].

   2. A lenticular form of a freshwater body under oceanic coasts [16].