Posidonia (Posidonia oceanica) is a marine flowering plant found in almost all shallow waters of the Mediterranean, and only in the Mediterranean; just as the olive tree is the symbol of the continental Mediterranean, posidonia characterizes the Mediterranean underwater .

Posidonia meadows are essential in the Mediterranean: they produce oxygen and nutrients, provide shelter for many species, filter water, dampen waves and currents, absorb our carbon dioxide…

But these underwater meadows are threatened by coastal development, pollution and tourism requirements. Although protected at a Mediterranean, European and sometimes national level, the meadow coverage has declined significantly over the past 50 years. The management of posidonia banquettes on beaches and the question of the destructive anchoring of yachts are two important themes related to posidonia.