Ten years ago UNESCO established a policy to protect shipwrecks over 100 years old.
The difficult question of how and if to protect more modern wrecks, particularly those in which people died, still exists.
Reportagem: Sam Wilson
Polish authorities recently banned divers from coming within 500 metres of the Wilhelm Gustloff. The German ship was sunk by a Soviet submarine in the Baltic Sea in 1945. More than 9,000 lives are thought to have been lost - the single largest death toll at sea.
Last month, seven European naval associations condemned Dutch salvage firms which they said were desecrating sailors' graves. They'd been searching for scrap metal aboard three British warships torpedoed and sunk off the Netherlands in 1914.
UNESCO's Convention on the Protection of Underwater Cultural Heritage, which was adopted ten years ago, does not apply in these cases, because it only protects shipwrecks more than 100 years old.
Whether ships and their dead should be left to rest in peace, or are sites of legitimate archaeological interest, can be a vexed and often emotional question.
Archaeologists say their job is the recovery and meticulous preservation of priceless artefacts. Many of them reject the label "treasure hunters".
But, with deep-sea exploration equipment costing tens of thousands of dollars a day, they need to cover their costs somehow. It's no surprise, then, that a ship laden with gold, silver and other valuables is seen as the greatest prize.
death toll (número de vítimas fatais) number of people who died
condemned (condenado, criticado duramente) critised very strongly
desecrating (profanando, destruindo e desrespeitando) damaging and showing no respect for
scrap metal (ferro-velho, metal de ítens abandonados que pode ser vendido para ser reutilizado) metal from old items which can be sold and then reused
adopted (aceito) accepted
legitimate (razoável e aceitável) reasonable and acceptable
vexed (complicado e polêmico, causando grande desentendimento) complicated and controversial, causing a lot of disagreement
meticulous (meticuloso, cuidadoso e extremamente detalhado) careful and extremely detailed
to cover their costs (cobrir seus custos, gerar dinheiro suficiente para pagar as despesas) to make enough money to pay for their expenses
laden with (carregado com, que leva uma grande carga de) with a big cargo of