The article is devoted to the report on the underwater archaeological research, July 03-20, 2006, where relicts of the late medieval bridge at Kryžiavonės kalva and Lake Plateliai area, Lithuania were investigated. The research work team was formed from two institutions. The students of Underwater Archaeology specialization together with members of Academic Club of Underwater Research, Department of Underwater Archaeology, UMK took part from Polish side. Underwater archaeologist Prof. Vladas Žulkus (KU Rector at present), scientific workers of Institute of Baltic Sea Region History and Archaeology together with Archaeology specialization students, Department of History, KU, took part at this project from Lithuanian side. The main goal of the works was clear localization and schematization of the bridge, preparing visual information (photos, paintings) of its particular details. Members of the working group had to define the Kryžiavonės kalva placement contours of the shoal, also making the detailed charts and paintings of the underwater locality.