Due to intensive and concentrated research activities during the last 10 to 15 yr, the quality of wet-welded joints has been improved to an extent that this process is currently regarded as a potential alternative to the more costly dry hyperbaric welding processes in comparable water depths. The wet welding process has matured to an interesting alternative repair process due to its high flexibility and versatility and its low investment costs with respect to achieving comparable weldment quality. However, due to the previous bad reputation of the poor weldment quality in former times, related to extremely high hardness, high porosity, high hydrogen contamination, and, in combination with this, high cracking susceptibility, the wet welding process still requires concentrated activities to improve its reputation and credibility, especially in European oil field application. New acceptance creiteria, more detailed information on the achievable weldment quality, and especially the development of life-predicting data for wet-welded components on the one hand, and new design criteria especially related to the process application in wet environment as well as excellent training of diver welders on the other hand, have been required. Advanced testing methods had to be applied, additional design criteria had to be developed, and achievable weldment quality data had to be included in acknowledged and approved standards and recommendations in training and certification standards for diver welders. All these data are now available. These results have been achieved with the financial support of the European Community through the THERMIE PROJECT FUNDING.