Underwater surveys around the site were carried out by Kurt Raveh, Shelley Wachsman and Saen Kingsley. Ephraim Stern, of the Institute of Archaeology at the Hebrew University, directed twenty seasons of excavations at the site between 1980 and 2000, in cooperation with the Israel Exploration Society and several Israeli, American, South African and Canadian academic institutions, as well as a large group of German volunteers. With 100–200 staff, students and volunteers per season Dor was one of the largest and longest-sustained excavation projects in Israel.[citation needed] The eleven excavation areas opened have revealed a wealth of information about the Iron Age, Persian, Hellenistic and Early Roman periods.