Abstract The experimental investigation of the corrosion resistance of welded shipbuilding and submarine steels with the optimum weld quality which can be used in the future for the improvement of the quality of already existing underwater marine systems (including oil platforms, bridge columns and ships) and for the construction of new and unfamiliar underwater sea-structures (including the submerged parts of Wave Energy Converters and Tidal Energy Converters) in many countries like Greece is an essential parameter from a technical, qualitative and economical point of view. This study presents, justifies and discusses the outputs of the experimental investigation of the corrosion resistance of three different welded steels (HY 100 steels, 316Ti and S355J2 + N) which are currently used in shipbuilding and submarine constructions.