The remains of a shipwreck at Serçce Liman, along the southern coast of Turkey, were recently excavated by the Institute of Nautical Archaeology. The wreck was that of a merchant ship which went down in about A.D. 1025. A major part of the cargo consisted of more than half-a-million fragments of broken glass vessels and chunks of glass cullet. The excavators wish to learn whether the ship was Byzantine or Islamic, to trace the final route of the ship, to identify the nationality of crew, and to learn where the glass was made. Identification of the proveniences of the cargo, the ship's fittings, and the personal belongings found on board could provide valuable evidence for answering these questions. Isotope determinations have been made for lead extracted from several lead-containing objects from the wreck. These include certain types of glasses, glazed ceramic wares, a bronze sword hilt, and a group of net sinkers. This study poses a severe test for the classification of objects and the determination of proveniences by lead isotopes studies, because the Eastern Mediterranean is a region notorious for the mixing and overlapping complications.