The Posidonia oceanica is suffering in various parts of the Mediterranean a significant regression in its area of distribution and in its populations. Specifically, in the Balearic Islands, it is estimated that its meadows have been reduced by up to 40% in the last 50 years. Scientific knowledge is essential to better understand the status of Posidonia meadows, and thus promote their protection and conservation. If we continue as before, it is likely that in a few decades we will have to lament the loss of all the posidonia meadows. For the conservation of these marine forests, it is necessary to implement management and conservation measures to mitigate their deterioration, combining local and global actions.