Page 125 - Manual for Activities directed at the Underwater Cultural Heritage

to stock timbers while avoiding their extraction from under water.
All of these techniques have their advantages, but also their limitations. Sandbags may change currents, textiles may block biological gas and thought should be given to these issues beforehand. Changes should be monitored that might occur in the condition of the site, in order to measure the effectiveness of the chosen in situ protection strategy and to be able to act upon any possible detrimental changes. The methodology for management projects should be well-chosen and should be as non-intrusive as possible.
Considerations on excavation
Excavation may produce important scientific results, but only if significant and up-to-date research questions have been formulated in advance. As excavation means destruction, it is irresponsible to excavate without knowing what research questions are asked: once a site is excavated, it has lost its most valuable and vulnerable information. Before taking such a drastic step, one needs to tread carefully and after much consideration. Is excavation indeed the correct choice? What are the questions that need answering? Would it be wise to test the questions elsewhere and then reconsider them for this par- ticular site? What other purposes can this site serve?
 © I. Radic´ Rossi. Fotodocumentation of the Croatian Conservation Institute. Diver above the protective cage at the 3rd - 4th century Cavat site, Croatia.
Cages, covering vulnerable underwater sites, have proven to be effective as physical protection and dissuasive element against pillage.The efficiency and duration of such protection depends heavily on the materials used and their fixation to the ground.They can be placed over a first sand layer. If maintenance and cleaning is ensured, divers can visit such sites looking through the cage or entering it with permission.This allows for cooperation with local diving centres which can obtain the right to visit with their diving tours in exchange for surveillance of the sites or a certain fee serving its protection. In Croatia, 8 underwater cultural heritage sites are protected by steel cages, which allow visitors to see them, but prevent their devastation.
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Objective, methodology and techniques