Ethics and Law
It is the special quality of water that archaeological objects - especially organic materials - are much better preserved. Hence recreational divers may find archaeological sites by chance, even without searching for them directly.
Up to the present day thirst for adventure and treasure-hunting mentality is evoked by lurid movies and sensational articles, without indicating the fatal consequences for the archaeology and the cultural heritage. If however objects are salvaged and exposed to air, they require immediate treatment by experts, otherwise the deterioration process would start very quickly, which is not reversible. Even artefacts that appear to be in a very good state might become very fragile once recovered, especially waterlogged wooden artefacts. Therefore the best practice is to leave objects in situ, i.e. untouched. Moreover only experts are able to make an estimation on the complexity of the site and its archaeological potential.
Up to the present day several states concede "claims" (in expectance in a share of the profit) to salvage companies, which exploit archaeological sites in their territorial waters. However the UNESCO and the Council of Europe have endeavoured over recent years to introduce an international legislation across national borders to rescue the cultural heritage, i.e. the 'Convention for the Protection of the Underwater Cultural Heritage'.
The continuing conflict between archaeologists and art market lobbyists is charged with tension. There are still serious gaps in the protection of archaeological artefacts against black market trade.