Wedescribehow specializeddatabasetechnology and data analysis methods were applied by the Swedish defense to help deal with the violation of Swedish marine territory by foreign submarine intruders during the Eighties and early Nineties. Among several approachestried some yielded interesting information, although most of the key questions remain unanswered.We conclude with a survey of belieffunction-andgenetic-aIgorithm-basedmethodswhichwere proposedto supportinterpretationof intelligence reportsand prediction of future submarinepositions,respectively.