There are a number of factors that contribute to the formation of a shipwreck, that can be divided into physical and cultural processes. A site can be affected by physical processes, that is, naturally occurring processes, such as the corrosion caused by salinity and ocean currents, or the growth of native and foreign marine organisms. It can also be affected by cultural processes, that is, by human interactions, such as adding or removing materials from the site of the wreck. Any archaeological activity, such as excavation, may also be considered invasive and tampering.