This chapter reviews the corrosion of the principal metals found in shipwrecks. It begins with a review of the theory of corrosion including Pourbaix diagrams, pH, temperature, salinity, dissolved oxygen, galvanic couples. Effects caused by the special environment of the shipwreck are also reviewed and include: water movement; sulphate-reducing bacteria and marine growths. The corrosion of the following metals is reviewed in more detail: iron, copper, brass and bronze, lead, tin, pewter, silver and its alloys, aluminum and gold.