© W. S. Maney & Son Ltd 2012 DOI 10.1179/1350503312Z.00000000040 conservation and mgmt of arch. sites, Vol. 14 Nos 1–4, 2012, 469–78 Complications and Effectiveness of In Situ Preservation Methods for Underwater Cultural Heritage Sites Sorna Khakzad and Konraad Van Balen Raymond Lemaire International Centre for Conservation, University of Leuven (KU Leuven), Belgium Underwater Cultural Heritage (UCH) as an outstanding division of the cultural heritage of humanity appears to be crucial and complicated when more general issues regarding preservation and conservation are raised. The essence of in situ preservation should be equally discussable for any kind of archaeological remains; on land or underwater. There is a long history of different methods and concepts of intervention in a variety of sub-aquatic archaeological sites; from shipwrecks to sub- merged settlements. This paper will present an introduction to different techniques and theories of preservation and conservation of underwater cultural and archaeological sites since this kind of heritage has scientifically been explored and studied. A range of different preservation methodologies, from total or partial transference inland, to preservation underwater, will be compared; the advantages and disadvantages of each option will be high- lighted. Different examples of international best practices will be illustrated. Different types of in situ conservation/protection will be explained and cat- egorized. Furthermore, there will be a focus on the UNESCO Convention of 2001 on Conservation and Preservation of UCH, where the in situ conservation option has been recommended. Moreover, the technical issue for preservation of UCH sites, either in situ or after displacement, will be explained. The implication of relocation for different sorts of sites and materials will be argued; for example, cases where some sites, such as shipwrecks, would more easily be displaced compared with submerged settlements, villages, or ports. Finally, by stressing that the state of ‘being underwater’ makes many sites qualified to be regarded as UCH, the in situ preservation approach will prevail that this state is maintained. keywords underwater cultural heritage, in situ conservation, evaluation systems