According to the Convention of the United Nations Educational, Science and Culture Organization (UNESCO), underwater cultural heritage are all traces of human existence, partially or totally submerged for more than 100 years. This includes sites, structures, buildings, artefacts and human remains, boats, aircraft and their cargo, together with their archaeological and natural context.

All these traces are part of the cultural heritage of humanity. Therefore access to submerged archaeological sites, to observe or document, should be encouraged. The aim is to stimulate the public’s taste for heritage and its safeguarding. However this access should be avoided when it is incompatible with its protection and management.

ARCHAEOLOGICAL DOCUMENT

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If we can compare the work of the archaeologist to that of the detective, we can say that the archaeological site is like the crime scene: the smallest details may be the key to deciphering the truth of the facts. That is why any change in the arrangement of traces, without a prior detailed and exhaustive record (scale design, photograph, three-dimensional positioning, etc.), may compromise research.

THE INTIMATE RELATIONSHIP BETWEEN THE ARCHAEOLOGICAL REMAINS OF A SITE IS CALLED ARCHAEOLOGICAL CONTEXT, ONE OF THE MOST IMPORTANT AREAS TO RETAIN

PRESERVATION OF TRACES

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The in situ preservation of underwater cultural heritage should always be considered as the first option, before any intervention is authorized or initiated, not least because archaeological assets from the aquatic environment pose very complicated conservation problems.

In any activity directed to underwater cultural heritage, non-destructive methods and techniques of prospecting should be used, rather than the recovery of objects. However, if excavation or recovery is necessary for the purpose of scientific studies or for the definitive protection of underwater cultural heritage, the methods and techniques used shall be as as destructive as possible and contribute to the preservation of traces. It must not be forgotten that the excavation and recovery of objects is like reading a book to which we tear out every page we read. You can’t read it again.

Therefore, the prospection, excavation and protection of underwater cultural heritage require the availability and application of special scientific methods and the use of appropriate techniques and equipment. Similarly, a high degree of expertise of the actors is necessary.

The recovered underwater cultural heritage must be deposited, preserved and managed in a way that ensures its long-term preservation, a complex and difficult task.

Objects and other archaeological remains from the aquatic environment present difficult conservation problems when exposed to air. Once dried, the organic materials (wood, leather, fabrics, etc.), some of them already very fragile in water, crate to the slightest touch. Even objects of a material as robust as iron, even if they are large (cannons, anchors), are reduced to rust dust in a few years. This degradation can only be avoided by keeping objects in a moist medium and subject to long chemical processes.

UNDERWATER ARCHAEOLOGICAL CAMPAIGN

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Given the fragility of submerged archaeological remains, it is easy to understand why, before any activity directed at underwater cultural heritage, a project plan is required to be appreciated and authorised by the competent authorities.

Interventions on underwater cultural heritage can only be carried out under the direction, control and regular presence of a qualified underwater archaeologist with adequate scientific competence to the project.

An environmental impact plan should also be prepared to ensure that seabed and marine life are not unduly disturbed.

A PROJECT PLAN SHOULD INCLUDE