Results of long-term current measurements in the Seine Bay are presented: (1) tidal flow and propagation of the tide across the bay; (2) ability to predict tidal currents from previous measurements by the means of harmonic analysis; (3) identification of residual flow factors according to a principal component analysis in a complex space; (4) description of the tidal residual flow with large eddies; (5) demonstration of wind effects on currents.