Practical Measures of Protection

Threats to the Underwater Cultural Heritage

With the increase of interest in underwater cultural heritage over the past decades, it is necessary to raise worldwide awareness of the value of sunken cultural heritage, and to engage decision makers in taking steps to protect these cultural treasures.

  • Economic activities  

The threats to underwater cultural heritage are multiple. The coasts, oceans and seabed are increasingly exploited and used for economic activities. Infrastructural projects in coastal areas or littoral zones can have a significant impact on underwater archaeological heritage. Many activities and construction works have an impact on the environment by generating pollution, causing erosion or modifying currents, and many of them can affect submerged archaeological sites, such as sunken cities or ancient wrecks.

To mitigate these undesirable industrial impacts, the 2001 Convention states in Article 5 that "Each State Party shall use the best practicable means at its disposal to prevent or mitigate any adverse effects that might arise from activities under its jurisdiction incidentally affecting underwater cultural heritage".

  • Commercial exploitation

Commercial exploitation is the legal recovery of artefacts from a heritage site with the aim of putting them up for sale. This phenomenon is especially to be observed on underwater archaeological sites. Commercial exploitation operations regularly violate scientific standards of excavation of archaeological sites

The 2001 Convention stipulates in Article 2.7 as overarching principle that underwater cultural heritage should not be commercially exploited. This regulation is in conformity with the moral principles that already apply to cultural heritage on land.

Every State, seeking to protect the world’s underwater heritage from commercial exploitation has an interest to ratify the 2001 Convention.

  • Pillages 

Modern equipment and technological tools facilitate underwater archaeology, but also allow for treasure hunting.  Extensive pillage is now also taking place under water.

Pillage is the theft of historical artefacts from a heritage site in violation of the law and without authorization.Diverse communities can be involved, ranging from occasional and opportunistic souvenir hunting by sport divers to specialized treasure-hunt enterprises. Pillage also often desecrates the grave sites. The 2001 Convention provides for strong measures, preventing the pillaging of underwater cultural heritage. They range from direct site protection measures to the interdiction of trafficking pillaged artefacts, port closure, seizure, sanctioning and international cooperation in the investigation and pursuit.

Every State, seeking to protect its underwater heritage from pillage has an interest to ratify the Convention.

Brochure on Pillaging

  • Climate change

Environmental changes, such as climate change, stronger erosion and current change can pose a threat to underwater cultural heritage sites. On the other hand underwater cultural heritage can, however, tell us a lot about historic climate change that once impacted the life of our ancestors.

It is a scientific fact, sea levels have been rising due to climate change. The relationship between rising sea levels and the vertical displacement of the earth’s crust lead to changes in the sea levels on the continental margin. Thus accounting for these changes is essential in planning and executing archaeological surveys on the continental shelf. Climate change can also lead to the destruction of many sites, due to a change in conservation patterns, change of currents and the introduction of new animal species in waters. 

Biological degradation of wooden wrecks occurs naturally. However, climate change is contributing to bacterial spread. Research on underwater cultural heritage must respect the environment. This is governed by the Rules annexed to the 2001 Convention. Environmental studies can also contribute to the preservation of underwater cultural heritage. 

  • Developing the seabed (mineral extraction, pipeline) 

Many underwater cultural heritage sites, especially however prehistoric now submerged, landscapes, are impacted by the extraction of sand and gravel ; which carries with it flint stones and bones. 

Though these industries are becoming regulated under national and international frameworks, in order to reconcile interests while protecting the sea bed, cultural sites need better monitoring, inventory and accurate data flow to balance economic interests and protection of the seabed.  Information about fragile heritage on the seabed is also needed in planning other marine activities such as cabling, dredging, fish farming, extracting gravel, laying pipelines, and renewable energy platform building. Developing the seabed in a way that facilitates the protection and research of underwater cultural heritage depends on the collaboration between academia and industry.

  • Trawling and fishing

Ancient fishing sites are of great archaeological interest, as for instance net weights and fishing hooks from historic periods are a source of knowledge both on fishing and on the site in question. Trawling activities are today a major issue concerning the preservation of underwater cultural heritage. Its impact on the sea floor is particularly devastating.

The 2001 Convention provides a comprehensive framework for increasing the legal and operational protection of underwater cultural heritage. In addition to the Convention, many practical tools and forms are available to protect underwater cultural heritage.

Practical Tools for Protection


Inventories are a key component of underwater cultural heritage management plans. They are indispensable in order to know, protect, preserve and research all underwater cultural heritage found.

Under the Convention, States Parties are obliged to establish a ‘competent authority’ and to provide for the establishment, maintenance and updating of an inventory of underwater cultural heritage (Art. 22). In practice, this inventory is the archive or the index to the archive in which cumulative information on existing heritage sites is retained.

The Meeting of States Parties to the 2001 Convention on the Protection of the Underwater Cultural Heritage adopted, on its 4th session, a Model Sheet for Inventories of Underwater Cultural Heritage  EN | FRES | AR | RU | ZH (Resolution 4/ MSP4 paragraph 8) in order to encourage the development of States Parties' own registers and to facilitate the management and protection of their submerged heritage. This Model Sheet can be used as a standard guideline to establish national registers of underwater cultural heritage, adapting it to the specific conditions and circumstances of every Member State.

Site Protection and supervision

The safeguarding of submerged archaeological sites needs effective site supervision and often also physical protection.

The safeguarding of submerged archaeological sites needs effective site supervision and often also physical protection.

  • Sonar buoys : float moored in water to mark a location, they may warn of danger, or indicate a navigational channel transmitting information to a base station on land. They can be installed in the parameters of an underwater archaeological site and may set off an alarm when a boat enters a particular zone. The alarm can also activate a camera or trigger the production of a satellite image transmitting information about the intruder to State authorities.


  • Satellite supervision : the movements of ships within protected zones, containing underwater cultural heritage, can be controlled by satellite High resolutions satellite images are taken by various satellites of certain maritime zones and a cartographic map is produced. Position changes of ships are in this way identified and vessels detected that violate the boundaries of protected areas.The data collected may serve also as prove in a court case.

Physical site protection

Sites that are not excavated and remain undisturbed may nevertheless undergo damage due to the impact of oxygen and aggression from organisms and chemicals in the water: infiltration in the pores, corrosion, colonization of algae and erosion are some to the immediate degradation processes of an artefact or of a structure, which can even lead to its total destruction. Once a site is surveyed, assessed and inventoried, it might therefore need protection from intrusion or decay, depending on its significance or fragility.

Such devices are varied and may be chosen according to the characteristics of the site. This protection can take the form of : 

  • Re-burial with layers of sand : this means does, however, make a later uncoverage for further research problematic.


  • Sand Bags : remains may be covered by sand bags and subsequent layers of sand.


  •  Fabric covers and nets : Sites may be reburied by a layer of hard-wearing fabric to create a barrier between the objects and the covering element and be stabilised by weights, such as sand bags. This has proven to be a cheap and effective way to protect sites from anchor damage, pillaging and to reach a stable conservation state. If such nets are loosely placed over a site, sediments that are moved over the seabed by tidal currents may continue to penetrate into the holes of the net and settle over the site, covering it within a few weeks, preventing abrasion. 


  • Protective Metal Nets : Protective metal nets may be used for the physical preservation of archaeological sites that are seriously threatened by vandalism or when waiting to be covered by more serious means of protection. They can take the form of simple iron nets reinforced or kept in the ground by cement blocks. The nets are after a certain period of time completely covered with marine organisms, impeding access to the underlying part. 


  • Cage Protection : Cages, covering vulnerable underwater sites, have proven to be effective not only as physical protection but also as a dissuasive element against pillage. The efficiency and duration of such protection depend 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 within the framework of their diving tours in exchange for surveillance of the sites or a certain fee serving its protection. 

Underwater Archaeology

Archaeological sites are very fragile and sensitive to intrusion. Even an intervention that opens a site for research purposes “damages” the archaeological information contained therein, as the site is no longer undisturbed. It is therefore important that information contained within the site is carefully recorded.

The 2001 Convention therefore regulates in its Annex, containing the “Rules concerning activities directed at underwater cultural heritage”, that only qualified and properly trained persons should be permitted to intervene on submerged sites.

Article 19.1 – Cooperation and information-sharing

States Parties shall cooperate and assist each other in the protection and management of underwater cultural heritage under this Convention, including, where practicable, collaborating in the investigation, excavation, documentation, conservation, study and presentation of such heritage.

Rules concerning activities directed at underwater cultural heritage

Rule 22. Activities directed at underwater cultural heritage shall only be undertaken under the direction and control of, and in the regular presence of, a qualified underwater archaeologist with scientific competence appropriate to the project.

Rule 23. All persons on the project team shall be qualified and have demonstrated competence appropriate to their roles in the project.

Heritage for Peace - Centenary of World War I

The Centenary of the First World War (1914-1918) is a unique opportunity to draw attention to the preservation of the World War I underwater cultural heritage and to its message for peace and reconciliation. 

An estimated 10 000 wrecks from the First World War can be found on seabeds around the world.  

Despite the fact that this heritage bears witness to one of the most significant conflicts in recent history, underwater cultural heritage from World War I has not yet been comprehensively studied. UNESCO calls on its Member States, and on society in general, to help preserve this unique submerged legacy - a legacy which is at once a powerful reminder of war, and a convincing voice for peace.   

As of 2014, World War I’s submerged heritage progressively falls under the protection of the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage.