The deep, elongated paralic basin of Kalloni bay has been studied through comparisons between several computed hydrodynamical situations and data collected in similar situations from its water body. These include salinities and phytoplanktonic biomasses. Additionally, sedimentological data, which integrate the environmental variations on the long term, have been collected in order to help in understanding the average biogeological functioning of the system. Depending upon its direction and speed, wind forcing induces different salinity and phytoplanktonic patterns. These generally display rather weak gradients from the entrance and the axial deepest channel towards the farthest northeastern reaches of the basin. Moreover, the ranges of salinities and phytoplanktonic biomasses display a very low degree of restriction from the sea (confinement), while the global phytoplanktonic composition, analysed by flow cytometry, shows the prominent marine influence over the basin. The average hydrodynamical conditions are dominated by the axial influx of marine water on the bottom, and by the surface-reflux of basinal waters along both side banks. Such a prevailing configuration is also displayed by sedimentological features. Kalloni bay appears as one of the less confined systems in the Mediterranean region, due to its shape and bathymetry, the absence of a sill between the basin and the sea, and active exchanges with the sea under the influence of wind activity.