The Marine Parks of Corse are extraordinary oasis, where an astonishing profusion of life is concentrated, that has no equal in any other part of the Tyrrhenian Sea. Our adventure evolves as a true treasure hunt: we explore the sea floor in search of a mysterious archaeological site, where a gigantic marble cross lies. Afterwards we sail northward to reach the most wild and remote coast of Corse. We dive in the waters of Scandola, a natural reserve created in 1975, where  protection is complete. In certain areas even swimming is prohibited. A primordial Mediterranean is awaiting for us there. This is the proof that this sea, if it were protected, could be just as splendid as the tropical paradises. We meet a team of biologists belonging to different countries, which have been leading a regular research on algae and marine plants for the last 8 years. They  warn us about the threat of the submerged forests of algae that are disappearing from the coasts of the western Mediterranean, with the exception of few areas:  Corse,  in Sardinia and in the Baleares. The return of the sea hawk, thanks to the initiative  of a ranger, has become the symbol of the success of this reserve.