The conservation of objects brought up from sea‐ or lake‐beds and other submerged environments poses special problems. Formidable difficulties arise at the very moment of discovery, while all treatments to ensure long‐term conservation must take into account various complex alterations to the deep structure of materials. As Colin Pearson points out in his chapter on conservation in Unesco's technical handbookProtection of the Underwater Heritage (1981): ‘it is of course impossible to cover in a few pages details of the deterioration of all types of objects that exist on a shipwreck or in a wet‐site, followed by complete guidelines on their conservation and restoration’. (See extracts inMuseum,Vol. XXXIV, No. I (inside back cover).) Today, published procedures and case‐histories abound and critical assessment of the state‐of‐the‐art should be possible. However, as Parks Canada's Victoria Jens‐sen observes, ‘only seasoned marine conservators or broad‐minded chemists can critically evaluate the usefulness of the literature’. Nevertheless, Victoria Jenssen herself is able to look evaluatively in the following article at a cross‐section of results achieved on various organic materials. She homes in on leather, whose problems typify perhaps those found in other waterlogged materials. Wood is, of course, the degraded organic material most commonly found; it is after all the medium of underwater archaeology's prime artefact, the ship. The conservation of waterlogged wood has been the focus of increased international exchange in recent years and co‐operation in this area has been directly furthered by Unesco. David Grattan from the Canadian Conservation Institute, Co‐ordinator of a Working Group on waterlogged wood in ICOM's International Committee for Conservation, takes a meas