The wreck site of the Australian First World War submarine HMAS AE2 in the Sea of Marmara had a salinity of 26 (parts per thousand) for the first 13 m, which increased to 41 at 21 m, after which it remained constant to the bottom at 72 m, where the dissolved oxygen was three parts per million. The vessel is protected by a very dense anaerobic concretion and lies half above a silt mound. Cross-sections of a concretion sample revealed the original surface, associated paint films and a series of burial-exposure episodes that reflected periodic changes in the silt levels, which are likely associated with major storms. Core samples of sediment have established the impact of the vessel on the site. Corrosion simulation experiments have established the direct linkage between chloride levels underneath the concretion layer and the pH of the entrapped solution. Following the initial drop camera survey, an ROV (Remote Observation Vehicle) examination of the interior of the boat showed a remarkable degree of preservation. A network of ten-tonnes of zinc anodes were distributed at the stern, amidships and the bow to bring about in-situ conservation of the historic submarine.
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