This essay aims to compile unexpected discoveries (all underwater) relating to the Mesolithic period. The disciplines concerned are beginning to realize that Mesolithic Europe (for example) was essentially a gigantic forest massif. As a result, the population lived mainly on the coast. Today, however, the ruins of their societies lie underwater. Why? Geology teaches us that they struggled for millennia against rising waters.In recent years, teams of European divers and researchers have "e;unearthed"e; the first clues about societies that may have planned and built large Neolithic megalithic sites. This represents a big change in our perception of Mesolithic hunter-gatherers.