The development of underwater archaeology and the increasing discovery of sites mean that conservation and restoration of this cultural heritage is essential to achieving full protection and long-term preservation of this legacy to humanity. Archaeologists and conservators must work together to study and preserve these discoveries, the fragility of which increases once removed from the water or their original context. Each profession must know the trade of the other. Archaeologists must understand the interactions between the environment and the materials in humid or submerged sites and must be ready to apply first aid techniques. The expertise of restorers must extend not only to rates of degradation and restoration and conservation techniques for different materials, but also to a first-hand knowledge of the underwater world through diving.