Pleistos

The Pleistos (, , ) is a river in central Greece. It drains the Pleistos valley, named after it, a relatively recent rift valley north of the Gulf of Corinth, and parallel to it. They have the same geologic causes. Being situated in karst topography, much of the river runs or seeps through underground channels. The surface stream is intermittent. However, the limestone riverbed reflecting the light gives the appearance of a stream of water.

The semi-arid valley floor, too inaccessible for urban development, is eminently suitable for dendriculture. Extensive olive groves, nicknamed the "sea of olives," have been in place since prehistoric times. The floor is flanked by precipitous elevations, notably a scarp on the north side. The primary access road to the valley runs on the side of the north scarp throughout its entire length.