Originally, in 2014, Laurent Ballesta had just one precise objective: to unravel the mystery of groupers. To understand the issues involved in their collective reproduction. But although focused on the study of groupers, the real surprise came from the sharks. Never before had the team been confronted with such a density of grey reef sharks. The divers took up the challenge of counting them. Methodically, they repeated the operation many times to arrive at the impressive figure of 700 grey reef sharks.