Within the last decade an intensive archaeological survey has been made on important relics of prehistoric settlements preserved in the great lakes of Upper Austria, concentrating on the Mondsee and Attersee. (Several areas are now threatened by ship traffic and other problems.) The article presents methods of organization and research, ways of surveying under water and documentation of the wooden piles and several findings. A table contains the results of the microscopic wood examination of the piles tested. -- AATA