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.
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.
Sam Wilson, BBC News
death toll: jumlah orang yang meninggal
condemned: mengkritik keras
dececrating: merusak atau tidak menghormati
metal: baja bekas yang dapat dijual atau digunakan kembali
legitimate: masuk akal
vexed: rumit dan kontroversial
meticulous: sangat teliti
to cover their costs: menutupi biaya pengeluaran mereka
laden with: penuh dengan muatan