The underwater branch of archaeology evolved from the need of exploration of the underwater sites. It evolved relatively late, due to the difficulties the archaeologists encountered in the research of these sites. It mainly uses the tools, skills and techniques used by the shipwreck explorers and salvagers. Since 1980, when it started to be part of the universities curricula, under the maritime archaeology name. It studies the activities, behaviours of past human cultures around and presently under the sea, rivers and estuaries, but also sites buried under water logged sediments.
From the last ice age, many lands were submerged due to the rise of the water level. The Northern Sea is one example. It was a great plain before. Also, as the human population always used water, many bridges and harbours are part of recent studies.
The ship wrenching are important not only because the make a contribution to our understanding of the past, but also to the circumstances accidents had happened, such as the case of Titanic, or the building technologies available at a certain point in time. UNESCO Convention on the Protection of the Underwater Culture Heritage protects any trace of human existence, that is at least one hundred years old.
In some cases, the sites are more difficult to access, compared to the ones that exist on dry land. Conditions such as the depth, accessibility to the diving site require special equipment and diving skills, but also use of remote technologies, such as submarines, sonar or remote sensing equipment. In addition, tidal flows, poor weather or dangerous marine creatures can restrict the access to the site. The objects found underwater are subject to movement by storms, currents, tidal flows or damage caused by storms or water erosion. Some of the artifacts on the bottom of the oceans, seas or rivers cannot be entirely recovered, due to their size or other aspects.