Decay This is also called site formation. In most oceans (except the Baltic Sea and a few other places), a shipwreck under water deteriorates rapidly during a first stage. This often takes decades for a wooden ship and about a century for a steel ship (shorter time in shallow water). What remains after that is usually stable for millennia if it remains covered by sand, sediment, coral, or other encrustions. A relatively stable wrecksite is usually in no urgent need of excavation, except for the risk of being destroyed by unexpected natural causes or human impact. It is often desirable to leave such a site untouched, saving money for conservation, and saving the site for future archaeologists, that probably will have better methods. More on degradation.