The International Day for the Biological Diversity (IDB), proclaimed by the United Nations 1993, when the Convention of Biological Diversity agreed in Nairobi came into force, is held on 22 May each year. For several decades now, experts have shown that biological diversity is an indispensable resource for the planet and an immeasurable wealth for local economies. To date 1,700,000 living species have been described, including animals, plants and micro-organisms belonging to the various kingdoms, but experts speculate that there may be as many as 13,000,000. A large proportion of species could be hiding in the oceans, which from the point of view of biodiversity are a real treasure trove still largely unknown. Although water covers two-thirds of the planet’s surface, we have explored only 5% of it. Yet there is also another factor to take into account when we count the number of species on the planet: by the end of the century, 50% of living species in fact risk extinction and it is precisely in order to raise our awareness on this issue that the International Day for Biological Diversity was established.