Freshwater fauna from 20 wells located 15-200 m from the seashore as well as marine interstitial fauna from the coastal zone around the village Aghios Georghios (Cape Likhada) have been investigated. Freshwater hypogean ostracods live mainly in protected wells having clean bottom and little particulate organic matter from which the water is moderately pumped. Epigean freshwater ostracods dominate in unprotected wells with large amounts of organic matter on the bottom. There is a sharp difference between the ostracod fauna living in fresh groundwater (mainly Cypridids) and those living in coastal marine interstitial habitats (marine Cytherids and Polycopids). It is suggested that in the Mediterranean realm the hypogean fauna could be found easily in protected wells with little organic matter accumulation, where water is moderately pumped.