Historical data from hydrological cruises performed off Peru by Instituto del Mar del Peru (IMARPE) during the years 2000-2004 are described and analysed. Hydrographic conditions commonly encountered are briefly described and contrasted with episodes displaying intense surface or subsurface salinity anomalies, in relation to calm wind conditions in summer, intense upwelling and strong mesoscale activity in winter and spring, as evidenced on sea level and wind data. These data suggest a strong variability at different spatial scales, related to a variety of coastal dynamical processes