I have a bit of basic knowledge on rusting and corrosion of iron but im trying to find ways to stop rusting. The problem is what if an object was already submerged in water? Is it still possible to stop it from rusting? I know there are 3 ways of preventing corrosion but im not sure if there are more. There is Galvanisation, Alloying and simply applying a layer of paint over an iron or steel object but will any of these methods work if the object is already underwater(around 1000m below sea level)? If not then, are there any more methods which could possibly slow down if not stop rusting?